[VA-API] [Webkit] cannot play video with hardware acceleration enabled
From
https://bugs.webkit.org/show_bug.cgi?id=232925
Ah, OK. Can you please report this at https://gitlab.freedesktop.org/gstreamer/gstreamer-vaapi/ then? Getting your issue to the correct issue tracker is essential if you want it fixed. :) Please include the two debug logs you attached above with your gstreamer-vaapi bug report, since they could be useful, and be sure to mention this only occurs when used in combination with WebKit's accelerated compositing mode.
We've seen plenty of similar bugs in the past, but since they're inevitably hardware-specific there's not much we can do about it here. This is the first time someone has identified that it depends on WebKit's accelerated compositing mode, though.