This file (and a couple others) are missing from packman ATM.
I’ve seen them (need version 0.10.30 or greater) at multimedia:/libs.
My doubt is, does these gstreamer packages housed at download.opensuse.org are limited due to DCMA/patent issues, like OOTB k3b/libxine are?
And is this so for other patent-related multimedia packages in general?
Thanks
Oops. Should have posted at multimedia forum, not here. My apologies.
Well, installing from the repo above gets rid from the missing gstreamer plugin messages (at least in subtitleeditor) but video and audio won’t play.
It seems that gstreamer in that repo is limited also.
There are _64 packages missing from Packman —again!
They are be back. Installing now.
I still had some trouble with some packages, not gstreamer though.
Like they were broken on the server.
It Works! Subtitleeditor now play video and audio for subtitle synchronization. 
Since oS 11.1 I had to use subtitleeditor in a oS 11.0 VM to get audio.
Note to those who upgraded to 11.3 and kept the /home hidden config files: I had to delete the old ~/.gstreamer-0.10/registry.x86_64.xml for it to work.
Well, thankfully they are working on it. Long live packman!