Various news articles state that Firefox supports h.264 on Windows since version 20. As of this writing the version is 24, yet Firefox still can't play most YouTube videos. I did the HTML5 opt-in and tested both Firefox and Nightly. I also made sure media.windows-media-foundation.enabled
in about:config
is enabled, and it is by default both on Firefox and Nightly.
What's wrong and how do I fix it?
Edit:
This video works.
This video fails.
They're both MP4 (right click video -> stats for nerds), so Firefox's h.264 support works at least some of the time.
Edit:
When I go to a YouTube video that doesn't work, click Share -> Embed and then copy-paste the src
of the iframe
tag into the address bar, the video works.
Best Answer
As a general comment, sometimes such problems are caused by missing codecs, fixed by installing a codecs pack such K-Lite. But as your videos do play when downloaded, this isn't your problem.
The video example that fails for you uses Flash, but you prefer the YouTube HTML5 player. More information is found in the article Force YouTube to Use the HTML5 Player:
EDIT : As userscripts.org has disappeared, I have modified the links to point to userscripts-mirror.org. In addition, I reproduce the script below :