On 23 August 2015 at 09:06, Heinz Diehl <htd+ml@fritha.org> wrote:
On 23.08.2015, Ahmad Samir wrote:

> I am not sure what exactly is happening on your system, but I'd try
> enabling MSE with h264, make sure these are set to true:
> media.fragmented-mp4.enabled
> media.fragmented-mp4.exposed
> media.fragmented-mp4.ffmpeg.enabled
> media.mediasource.mp4.enabled

Thanks a lot for highly valuable information, you made my day!
With these options enabled and webm disabled, I'm able to play both
highres videos and all the other non-highres ones that didn't work.

The blocker for those other videos was MSE & WebM VP9 being
enabled. Now, Firefox uses MSE & H.264 and does exactly what I want it
to do.


youtube seems to prefer mp4/h264 over webm/vp{8,9}, so if your system supports both, youtube will default to playing mp4/h264.

And it seems that MSE support is much better with FF40; I remember testing it with older versions a couple of months ago and it was awful.

--
Ahmad Samir