By default, Firefox is not playing any video unless I install Flash, which I won’t. The only video it’s playing are Youtube videos if I choose the HTML5 player, however since… July-August, by default Firefox no longer need Flash.
So what may be the problem? I can confirm it’s only happening on OpenSUSE. (got installations right now of Debian, Kali, Ubuntu and Windows, no need Flash at any of them)
for restricted formats you need packman
goto yast->repository management->add->community repo’s->select packman
goto software management->repository select packman click on the blue link that says switch system packages to this reposetory
see these wiki’s for more info, they’ve got nice picture’s too
https://en.opensuse.org/SDB:Add_package_repositories
https://en.opensuse.org/SDB:Vendor_change_update#Full_repository_Vendor_change
or for the lazy copy/paste this in a terminal like konsole
sudo zypper ar -f http://ftp.gwdg.de/pub/linux/misc/packman/suse/openSUSE_Leap_42.1/ packman
sudo zypper ref
sudo zypper dup --from packman
ps copy and paste line by line not the whole thing
guess you didn’t understand my question.
Mmm checking further right now, it seems to be something related to Firefox and not OpenSUSE. In Debian, Iceweasel (Firefox fork) doesn’t need Flash, but if I install Firefox, it does.
So in summary, Firefox n Windows and Iceweasel in Debian don’t need Flash, but Firefox in Linux seems to need it.
They do need flash it is just auto installed. Note the name of the Linux, openSUSE. Note the word open. It does not ship with ANY proprietary software and flash is proprietary . 
Please, if you don’t know, don’t make such affirmations.
They don’t ship flash built-in
Right. Only Chrome does AFAIK.
Can you point to any site that works in those other systems you mention (without Flash) but not with openSUSE’s Firefox?
Also, do you have all necessary codecs installed?
AFAIK, Firefox uses gstreamer for HTML5, so you probably need gstreamer-plugins-bad-addon, gstreamer-plugins-ugly-orig-addon and/or gstreamer-plugins-libav from Packman.
And you should do a full switch to Packman too, to make sure that the underlying system libraries are not crippled.
Like described here:
https://en.opensuse.org/SDB:Vendor_change_update#Full_repository_Vendor_change
no you didn’t understand restricted codecs and you wore just there reading why there is no full ffmpeg in openSUSE.
Firefox uses the OS’s build in video and audio decoders for mp4 files, if your setup can not play mp4 files neither can firefox, Firefox has 2 options of rendering restricted formats by using gstreamer (default) or by using ffmpeg (can be set by modifying media.fragmented-mp4.ffmpeg.enabled in about:config)
to get support for mp4 files you need to add and set packman as the system repo you do that by following my advice.
OK you have an option of a totally open/free web video experience but that depends on the server side, like does it host the file in webm format with vp8 (vp9) video and ogg audio, Firefox under openSUSE can natively decode webm but check if you have libwebm/libvp8(9)/libogg installed.
being partially knowledgeable of Debian’s I can assure you IceWeasel can not decode mp4 video’s without using extra non free packages, the only deb based OS I know that distributes patented non free codecs is Mint and that’s because they’re based in Ireland where they don’t have software patents
I was missing the ugly and the libav, so either of them, or both, solved the issue.