I am pretty sure the problem is in the GitHub - cisco/openh264: Open Source H.264 Codec codec - an open implementation of H.264, created so that H.264 could be used in WebRTC specification (well, I have no prooflinks, but that seems plausible).
Because openh264 is open source with fees paid by Cisco, it ships in Fedora and other pure flavor Linux systems by default. I have yet to confirm that the bug with developers, but I see no other reason how my Firefox is different from foxes of other people here who reported that learning materials load and play successfully.
I see that the Operating Systems video is encoded by x264 codes, and it looks like it encodes with more features than open264 is able to decode. Because of the H.264 royalties. Fedora and other legal clear systems can not ship it, and that’s the result of why I wasted so much time over the last few years struggling with various video problems here.
The solution for LDLAI is to use royalty free codecs like AV1 with DASH or whatever modern and royalty free format and container YouTube/Netflix use to stream their content.
For myself I see no other solution right now than to see how to tryopenh264 update (Releases · cisco/openh264 · GitHub), ensure that the problem is not solved, report the bug, and switch to x264 somehow.
