Disable "forced" compatibility mode on YouTube?

[__NM64__]

I noticed that YouTube refuses to serve DASH VP9/WebM video streams when Firefox compatibility mode is enabled. This was easy to work around in Pale Moon 25 since I could just disable the setting in options, but PM 26 seems to force Firefox compatibility mode even when I have that setting disabled in said options.

So how can I go about disabling what seems to be "Forced" compatibility mode?


For reference, I use ViewTube (LINK) to access the DASH VP9/WebM video streams.

If you need an example video to test with, I normally use these:
Still image: https://www.youtube.com/watch?v=kw9fsQbukJ4
60fps video: https://www.youtube.com/watch?v=a-mBnpsuHgM


In Pale Moon 25, with compatibility mode turned off, you will find various "High Definition WebM" formats listed in ViewTube's drop-down menu; if you turn compatibility mode on then reload the page, none of the "High Definition WebM" formats will be listed.

[coffeebreak]

PM 26 seems to force Firefox compatibility mode even when I have that setting disabled in said options.

So how can I go about disabling what seems to be "Forced" compatibility mode?

I haven't used ViewTube but maybe this will help.

-- PM 26 shipped with a custom useragent override for Youtube so you'd need to delete that value to allow the regular compatMode settings (or lack thereof) to take effect for youtube.com.

-- Don't know if this matters but: PM 26 (unlike 25.8.1) has two compatMode preferences, one for Firefox, one for Gecko. The front end setting in the Options panel only affects the Firefox preference. To turn off the Gecko preference you have to go to about:config and toggle general.useragent.compatMode.gecko to false.

Also Youtube just modified it's browser version support policy -- timing-wise, coincides with FF 44 release (my opinion) -- and it's caused access problems. More on that in this thread.

[Moonchild]

You will have to replace the value of the pre-set YouTube override in about:config with a value of your choice that works for your script.
This was pre-set because not having it set would make it directly dependent on other settings and by default not even work correctly. As long as YouTube keeps doing useragent checks, and continues to do it incorrectly or not complete, we will be forced to have overrides in place for them to feed them something that makes it work for our users who just want to watch videos.

[cartel]

PM 26 over-wrote my useragent for YT I think.

Changed it to this to get html5 back.

general.useragent.override.youtube.com
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Firefox/38.0

[__NM64__]

general.useragent.override.youtube.com

Oh, at the time of making this thread I didn't realize that I could just use this setting to work around this issue. I've used it before as a per-site compatibility mode, and it never occurred to me that I can basically use it to disable compatibility mode as well.

Simply setting the useragent for youtube.com to be the default Pale Moon user agent "fixed" the issue.