Firefox will not load videos on YouTube Mobile. It states that Flash needs to be updated, but it works fine in the Android browser.
When I browse to YouTube mobile (http://m.youtube.com/), and click on a video, it takes me to the video's mobile page. Once I click on the video itself (to play), it redirects me to the desktop version of the same video page and tells me I need to update my Flash plugin.
Until earlier today, it was not redirecting me to the desktop pages, but now it is.
Opaite Mbohovái (1)
Sorry, Flash for Android is not yet compatible with Firefox for Android. We hope to work with Adobe to fix this in a future release.
You can play some YouTube videos by enabling YouTube's HTML5 beta. Only videos available in the WebM or Theora formats will play in Firefox for Android: http://youtube.com/html5