Was trying to watch the state of the union and got an error from the youtube embed saying my browser did not recognize the video format. Had a link about HTML5 video that goes to http://youtube-nocookie.com/html5 which of course 404's

Standalone video works fine for me. Trying out e.g, France 24's Live Stream (https://www.youtube.com/watch?v=BFwedk4dBCc), under our user-agent they display the error on the player: "Live event playback is not supported on this client." Inspecting the player reveals a stream mime type video/mp4; codecs="avc1.4d401e" with HTTPS streaming.

This requires some MediaSource Extension stuff, apparently. In a nightly build with all MSE-related stuff in about:config enables, YouTube *tries* to play the France24 stream. Not quite successfully but it seems to be failing on our end. Hence, I don't think this is a Tech Evangelism issue - it's more about getting MSE support out with sufficient quality.

Let's set as being blocked by 778617, then re-check when we're shipping.

FWIW, I see a CORS error in the console on the France 24 channel. I didn't investigate, but if that's one of the media segments it would cause the buffering hang I see, and be a problem with youtube's site. We're hoping to ship MSE for youtube on windows only in Firefox 36, so you can help us out by testing things with Beta on Windows, or Nightly on Windows or Mac.

Looks like this bug is solved. I can play France 24 live channel @YouTube HTML5 player without any problem. Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:37.0) Gecko/20100101 Firefox/37.0

With MacOSX Yosemite: 1. Going to https://www.youtube.com/html5 2. Select HTML5 player by default. 3. Using Firefox 36.0.1 on https://www.youtube.com/watch?v=BFwedk4dBCc The flashplayer is used. 4. Using Firefox 39.0a1 (2015-03-10) on the same video. The HTML5 player is used. The video jumps from a still image to another one every 5 to 10s and there is no sound.

Closing this bug.