Recently I've been having trouble playing video in Firefox reliably.
Often the same video that played a moment ago, then won't play after navigating away and back.
This is what I see instead:
When I follow the link...
It shows that HTML5 video is supported by my browser:
It is annotated with an asterisk that H.264 playback depends on hardware and operating system support. I have trouble believing that my OS (macOS 10.12.6) or my hardware (a fairly recent MacBook Pro) is incapable of playing H.264 video... especially since I watched YouTube videos on it, in Firefox, for a long time prior to this without any problems. I keep Firefox up to date (currently v64.0). And the wording "depends on hardware and operating system support" is pretty vague, leaving me wondering where to look next to troubleshoot this.
I did find a similar question on Stack Exchange, but the accepted answer is not applicable to me because in about:config I do not have the entries rsa_rc4_128_sha/rsa_rc4_128_md5 mentioned in that answer. My issue may still be related to SSL in a different way, but I am left guessing at this point.
Any suggestions would be appreciated.