28 Nov 15 How to enable HTML5 video playback in firefox

If you use Mozilla Firefox and you want to view video streaming with HTML5 embedded players, you may need to enable some video functionality into the firefox configuration.
For some reason obscure to me Mozilla Firefox will not play some HTML5 based video streaming, and the embedded player will probably fall back to Adobe Flash based streaming (that is what I don’t want since it’s closed source and it’s a very insecure application).

For example, youtube has a HTML5 based player that you could choose to use instead of flv. You can verify and enable HTML5 based streaming functionality of your browser navigating to https://www.youtube.com/html5.

In my case (Firefox 64 bit on Linux Debian) the tabs “Media Source Extensions”, “MSE & H.264” and “MSE & WebM VP9” are disabled by default.

If you want to enable those functionalities simply write “about:config” into the firefox navigation bar.
You will be alerted to pay attention to not modify things or your warranty will be broken.
Just ignore the warning and proceed.

Now, if you did not already, switch the following configuration parameters to true:

media.fragmented-mp4.exposed
media.fragmented-mp4.ffmpeg.enabled
media.fragmented-mp4.gmp.enabled
media.mediasource.webm.enabled
media.mediasource.enabled

If you try to refresh the HTML5 based youtube player, you should hopefully have all video streaming tabs ready and enabled.
If you want, you can now switch the youtube default player to HTML5.