Thanks! There is some progress, all sites I’ve tried now play both video and audio (youtube.com, bbc.com, v.reddit.com, piped.video, yewtu.be, etc).
However, there is no longer hardware acceleration for video decoding, as far as I can tell. With 4.4.x, I was able to play YouTube 1080p with no dropped frames on my XA2. With 4.5.x, even 480p videos on YouTube are dropping frames. Please see the attached images for comparing the nerd info on the same YouTube video before and after the updated to 4.5.x.
(You might think it’s the change of video codec for the served video, but I’ve tried forcing VP9 on piped.video and it didn’t play 1080p as before anyway.)