Thank you, Martin!
I've just updated the wiki page to remove the rdd stuff which should no longer be
necessary with Firefox 96.
Thanks to the wiki page, one can check whether hardware acceleration is available.
Is there any indication (e.g. in about:support) to see whether video hardware acceleration
is working? Or any tool to check?
Is hardware acceleration a prerequisite for using VA-API accelerated video decoding?
(Background: my GPU is too old to get hardware acceleration support in firefox, but I do
have VA-API with some video decoding support in hardware).