How to play H264 video in Firefox on Linux?

Question

Video

Hello!
Help me to understand.
OpenSuse 42.2 Firefox 50 YouTube plays fine, but videos don't play on other sites. Writes that h264 support is needed in the browser.
As far as I understand, OpenH264 is only licensed for calls. What plugin still needs to be installed to play video online?

Answer 1

You need to enable the packman repository.
https://ru.opensuse.org/%D0%94%D0%BE%D0%BF%D0%BE%D...

Answer 2

After the next OS update, everything was covered with a copper basin along with the OS, so I'm doing it all over again.
This time I did not switch system packages to packman. I limited myself to translating libavcodec (+ what is needed according to dependencies.
Accordingly, I put 2 questions on the agenda:
1) is libavcodec needed only for playing video in firefox or in general for any video in the system (for example, in VLC)?
I mean, is the codec common to the entire system or do programs like VLC have their own assemblies? And I'm afraid of conflict.
2) After I connected the packman repository and transferred libavcodec to it, now all programs will look at the new repository when updating, or just libavcodec? I still want to take the main programs from the opensuse repository.