It looks like this has been silently fixed in 4.6! Both AVC1 and VP9 videos on YouTube seem to be played with accelerated decoding on my XA2 with SFOS 4.6.0.13 (Sauna). 1080p YT videos are again silky smooth on my device and 780p@60 videos are played with very few dropped frames, just like on SFOS 4.4. Thank you!
I’m enclosing screenshots for the above two videos to compare. AVC decoding seems to be marginally better, but I had to disable VP9 support altogether in about:config for that, something that’s probably not worth the gain…
