With the update to ffmpeg 6.0, I wasn't able to play videos in firefox. Perhaps on some websites it's possible, but for me I wasn't able to watch any videos.
If we downgrade to ffmpeg 5.1.2 there is no problem anymore. I was able to build firefox 111.0 with a fix and now I can watch videos. For the build, the following patches are needed:
0001-Bug-1819374-Squashed-ffmpeg-6.0-update.patch0002-Bug-1820416-Use-correct-FFVPX-headers-from-ffmpeg-6..patch
note: the patches need to be regenerated to fix patching with busybox patch. https://codeberg.org/kiss-community/repo/issues/139