@FirefoxNightly There's something wrong with @YouTube playback on 69.0a1. The video stops playing whenever I move the mouse away from the video. Even when I keep the mouse on the video, it will still stop playing once the video tools disappear. Audio keeps playing, though.
I did. Video is still freezing. Not only on YT BTW. The problem manifested itself with the latest nightly build, it's probably in Firefox devs' hands.