Loading a video in GTK-based subtitleeditor opens a error dialog:
GStreamer plugins missing.
The playback of this movie requires the following decoders which are not installed:

MPEG-4 Video Decoder (Advanced Simple Profile)
from the command line:
Code:
** (subtitleeditor:31659): WARNING **:  Decoder not available for type "video/mpeg, mpegversion=(int)4,  systemstream=(boolean)false, framerate=(fraction)24/1, width=(int)720,  height=(int)392,  codec_data=(buffer)000001b0f5000001b509000001000000012008868400630c5a10c45263000001b244697658353033623133393370000001b25876694430303634,  parsed=(boolean)true, profile=(string)advanced-simple, level=(string)5,  pixel-aspect-ratio=(fraction)1/1". [gsturidecodebin.c(939):  unknown_type_cb ():  /gtkmm__GstPlayBin:pipeline/GstURIDecodeBin:uridecodebin0]
Erasing the existing ~/.cache/gstreamer-1.0/registry.x86_64.bin just recreates it.

However it seems that GStreamer is installed from a mix of Oss and packman repos, although I did a full system switch (twice...):
Code:
# zypper se -i -s gstreamer
...
S  | Nome                         | Tipo       | Versão      | Arquitetura | Repositório           
---+------------------------------+------------+-------------+-------------+-----------------------
i+ | GStreamer Multimedia Codecs  | aplicativo |             | noarch      | multimedia:libs       
i+ | PackageKit-gstreamer-plugin  | pacote     | 1.1.3-4.4   | x86_64      | openSUSE:Leap:42.3    
i+ | PackageKit-gstreamer-plugin  | pacote     | 1.1.3-4.4   | x86_64      | openSUSE-Leap-42.3-Oss
i+ | gstreamer                    | pacote     | 1.8.3-4.13  | x86_64      | openSUSE:Leap:42.3    
i+ | gstreamer                    | pacote     | 1.8.3-4.13  | x86_64      | openSUSE-Leap-42.3-Oss
i  | gstreamer-fluendo-mp3        | pacote     | 21-18.2     | x86_64      | multimedia:libs       
i+ | gstreamer-lang               | pacote     | 1.8.3-4.13  | noarch      | openSUSE:Leap:42.3    
i+ | gstreamer-lang               | pacote     | 1.8.3-4.13  | noarch      | openSUSE-Leap-42.3-Oss
i+ | gstreamer-libnice            | pacote     | 0.1.13-6.3  | x86_64      | openSUSE:Leap:42.3    
i+ | gstreamer-libnice            | pacote     | 0.1.13-6.3  | x86_64      | openSUSE-Leap-42.3-Oss
i+ | gstreamer-plugins-bad        | pacote     | 1.8.3-8.10  | x86_64      | Packman Repository    
i+ | gstreamer-plugins-bad-lang   | pacote     | 1.8.3-8.10  | noarch      | Packman Repository    
i+ | gstreamer-plugins-base       | pacote     | 1.8.3-7.16  | x86_64      | openSUSE:Leap:42.3    
i+ | gstreamer-plugins-base       | pacote     | 1.8.3-7.16  | x86_64      | openSUSE-Leap-42.3-Oss
i+ | gstreamer-plugins-base-lang  | pacote     | 1.8.3-7.16  | noarch      | openSUSE:Leap:42.3    
i+ | gstreamer-plugins-base-lang  | pacote     | 1.8.3-7.16  | noarch      | openSUSE-Leap-42.3-Oss
i+ | gstreamer-plugins-farstream  | pacote     | 0.2.8-3.4   | x86_64      | openSUSE:Leap:42.3                                                             
i+ | gstreamer-plugins-farstream  | pacote     | 0.2.8-3.4   | x86_64      | openSUSE-Leap-42.3-Oss                                                         
i+ | gstreamer-plugins-good       | pacote     | 1.8.3-8.1   | x86_64      | openSUSE:Leap:42.3                                                             
i+ | gstreamer-plugins-good       | pacote     | 1.8.3-8.1   | x86_64      | openSUSE-Leap-42.3-Oss                                                         
i+ | gstreamer-plugins-good-lang  | pacote     | 1.8.3-8.1   | noarch      | openSUSE:Leap:42.3    
i+ | gstreamer-plugins-good-lang  | pacote     | 1.8.3-8.1   | noarch      | openSUSE-Leap-42.3-Oss
i+ | gstreamer-plugins-ugly       | pacote     | 1.8.3-10.3  | x86_64      | Packman Repository    
i+ | gstreamer-plugins-ugly-lang  | pacote     | 1.8.3-10.3  | noarch      | Packman Repository    
i+ | libgstreamer-1_0-0           | pacote     | 1.8.3-4.13  | x86_64      | openSUSE:Leap:42.3    
i+ | libgstreamer-1_0-0           | pacote     | 1.8.3-4.13  | x86_64      | openSUSE-Leap-42.3-Oss
i+ | libgstreamer-1_0-0-32bit     | pacote     | 1.8.3-4.13  | x86_64      | openSUSE:Leap:42.3    
i+ | libgstreamer-1_0-0-32bit     | pacote     | 1.8.3-4.13  | x86_64      | openSUSE-Leap-42.3-Oss
i+ | libgstreamermm-1_0-1         | pacote     | 1.10.0-10.5 | x86_64      | (Pacotes do sistema)  
i+ | phonon-backend-gstreamer     | pacote     | 4.8.2-6.2   | x86_64      | openSUSE:Leap:42.3    
i+ | phonon-backend-gstreamer     | pacote     | 4.8.2-6.2   | x86_64      | openSUSE-Leap-42.3-Oss
i+ | phonon4qt5-backend-gstreamer | pacote     | 4.9.0-3.2   | x86_64      | openSUSE:Leap:42.3    
i+ | phonon4qt5-backend-gstreamer | pacote     | 4.9.0-3.2   | x86_64      | openSUSE-Leap-42.3-Oss
Packman repo is
Code:
# zypper lr -d
Prioridades de repositório em vigor:                                                                                     (Veja 'zypper lr -P' para detalhes)
      90 (maior prioridade)  :  1 repositório 
      99 (prioridade padrão) : 16 repositórios

#  | Apelido                             | Nome                                    | Habilitado | Verificação GPG | Atualizar | Prioridade | Tipo     | URI                                                                                                | Serviço
---+-------------------------------------+-----------------------------------------+------------+-----------------+-----------+------------+----------+----------------------------------------------------------------------------------------------------+--------
 1 | RPM                                 | RPM                                     | Sim        | ( p) Sim        | Não       |   99       | plaindir | dir:///home/blimmer/bin/RPM                                                                        |        
 2 | download.nvidia.com-leap            | nVidia Graphics Drivers                 | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | https://download.nvidia.com/opensuse/leap/42.3                                                     |        
 3 | http-download.opensuse.org-0372629c | multimedia:libs                         | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/multimedia:/libs/openSUSE_Leap_42.3/                     |        
 4 | http-download.opensuse.org-047051c4 | games                                   | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/games/openSUSE_Leap_42.3/                                |        
 5 | http-download.opensuse.org-0a7d84ea | home:wolfi323:branches:KDE:Extra        | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/home:/wolfi323:/branches:/KDE:/Extra/openSUSE_Leap_42.3/ |        
 6 | http-download.opensuse.org-2ae7a8f4 | openSUSE:Leap:42.3:NonFree              | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/openSUSE:/Leap:/42.3:/NonFree/standard/                  |        
 7 | http-download.opensuse.org-399f560c | KDE:Extra                               | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/KDE:/Extra/openSUSE_Leap_42.3/                           |        
 8 | http-download.opensuse.org-3f22ca8f | openSUSE:Leap:42.3                      | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/openSUSE:/Leap:/42.3/standard/                           |        
 9 | http-download.opensuse.org-86b6ab76 | multimedia:apps                         | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/multimedia:/apps/openSUSE_Leap_42.3/                     |        
10 | http-download.opensuse.org-b2b49118 | home:Sauerland                          | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/home:/Sauerland/openSUSE_Leap_42.3/                      |        
11 | http-download.opensuse.org-da9cb22c | games:tools                             | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/repositories/games:/tools/openSUSE_Leap_42.3/                         |        
12 | openSUSE-Leap-42.3-0                | openSUSE-Leap-42.3-0                    | Não        | ----            | ----      |   99       | yast2    | cd:///?devices=/dev/disk/by-id/ata-ATAPI_iHAS122_F_3522551_2E8712501382                            |        
13 | opensuse-guide.org-repo             | Libdvdcss Repository                    | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://opensuse-guide.org/repo/openSUSE_Leap_42.3/                                                 |        
14 | packman.inode.at-suse               | Packman Repository                      | Sim        | (r ) Sim        | Sim       |   90       | rpm-md   | http://packman.inode.at/suse/openSUSE_Leap_42.3/                                                   |        
15 | repo-debug                          | openSUSE-Leap-42.3-Debug                | Não        | ----            | ----      |   99       | NONE     | http://download.opensuse.org/debug/distribution/leap/42.3/repo/oss/                                |        
16 | repo-debug-non-oss                  | openSUSE-Leap-42.3-Debug-Non-Oss        | Não        | ----            | ----      |   99       | NONE     | http://download.opensuse.org/debug/distribution/leap/42.3/repo/non-oss/                            |        
17 | repo-debug-update                   | openSUSE-Leap-42.3-Update-Debug         | Não        | ----            | ----      |   99       | NONE     | http://download.opensuse.org/debug/update/leap/42.3/oss/                                           |        
18 | repo-debug-update-non-oss           | openSUSE-Leap-42.3-Update-Debug-Non-Oss | Não        | ----            | ----      |   99       | NONE     | http://download.opensuse.org/debug/update/leap/42.3/non-oss/                                       |        
19 | repo-non-oss                        | openSUSE-Leap-42.3-Non-Oss              | Sim        | (r ) Sim        | Sim       |   99       | yast2    | http://download.opensuse.org/distribution/leap/42.3/repo/non-oss/                                  |        
20 | repo-oss                            | openSUSE-Leap-42.3-Oss                  | Sim        | (r ) Sim        | Sim       |   99       | yast2    | http://download.opensuse.org/distribution/leap/42.3/repo/oss/                                      |        
21 | repo-source                         | openSUSE-Leap-42.3-Source               | Não        | ----            | ----      |   99       | NONE     | http://download.opensuse.org/source/distribution/leap/42.3/repo/oss/                               |        
22 | repo-source-non-oss                 | openSUSE-Leap-42.3-Source-Non-Oss       | Não        | ----            | ----      |   99       | NONE     | http://download.opensuse.org/source/distribution/leap/42.3/repo/non-oss/                           |        
23 | repo-update                         | openSUSE-Leap-42.3-Update               | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/update/leap/42.3/oss/                                                 |        
24 | repo-update-non-oss                 | openSUSE-Leap-42.3-Update-Non-Oss       | Sim        | (r ) Sim        | Sim       |   99       | rpm-md   | http://download.opensuse.org/update/leap/42.3/non-oss/
Packman has higher 90 priority, all others are 99.

What am I not seeing?

Thanks.