Cfrgtkky

Youtube HTML5 is not working anymore after I upgraded to Firefox Nightly 57.0a1. Anyone got it to work?

On the same machine (Ubuntu 16.04) I have Chromium browser, where all the Youtube HTML5 options are working.

Also, it seems impossible to make Youtube work with the Flash player on Firefox. I tried the "official" way by turning media.autoplay.enabled to false. I also tried to change the user agent to Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:21.0) Gecko/20130331 Firefox/21.0 - both did nothing to convince Youtube to use Flash!

Here is what I have tried so far:

I have run

sudo apt-get install ubuntu-restricted-extras

as was recommended here https://askubuntu.com/a/436336

but it did not change the status on the Firefox Youtube page below (so why was that stuff needed?)

Also I have set the following in Firefox about:config

media.mediasource.enabled; true

media.mediasource.format-reader; true

media.mediasource.format-reader.webm; true

media.mediasource.mp4.enabled; true

media.mediasource.webm.enabled; true



media.fragmented-mp4.enabled; true

media.fragmented-mp4.exposed; true

media.fragmented-mp4.ffmpeg.enabled; true

media.fragmented-mp4.gmp.enabled; true

media.fragmented-mp4.use-blank-decoder; false

as appears here https://www.youtube.com/watch?v=OUfCsSch8Zk although it looks outdated: some of the preferences did not exist, so I tried to add them anyway... but it changed nothing on the Firefox Youtube page below.

What does this browser support?

https://www.youtube.com/html5

Firefox Nightly (running in safe mode)

57.0a1 (2017-08-03) (64-bit)

Chromium

Chromium 59.0.3071.109 Built on Ubuntu , running on Ubuntu 16.04

By installing the nightly's builds, you like to live dangerously

The actual stable version is the 54, and you are with the version 57... Just to let you know that nightly build version are mostly experimental version.

in All cases going on the Firefox website there > https://www.mozilla.org/en-US/firefox/new/ might help you alot.
Then click on the blue button "Refresh FireFox" beside the green button
it might help you a lot by refrefreshing firefox

or go there > https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings?utm_source=mozilla.org&utm_medium=referral&utm_campaign=learn-more-link
To do it from the browser itself

Note: your add-ons will be reset as well as your settings, but you will still have your passwords and so.

EDIT: If it's for the container tabs, it's already in the "normal" Firefox (V 54), but it's disabled (false) by default >
So, you can instal the V54 stable then go to the about:config pref privacy.userContext.enabled and set it to 'true' by double clicking on the line, I just did it ;) (that's a cool feature BTW)
you might need to restart firefox

https://wiki.mozilla.org/Security/Contextual_Identity_Project/Containers

EDIT 2 : Might it be possible that it come from your distro too?
I am on ubuntu-MATE (the distro > https://ubuntu-mate.org/) and have not problem at all (see below the screen shot) and the FireFox i am using is the one installed by default on the distro and flash is not installed (i don't want it).