After updating Firefox from 78 to 79, hardware-accelerated video decoding no longer works properly in Wayland: streaming video gets cut off with an error message from the service.
== Steps to reproduce ==
1. Follow the steps in  to enable VA-API.
2. Open a Youtube/Twitch video (for instance https://www.twitch.tv/rifftrax), press play
== What I expect to happen ==
For the video be played without issues (as it did with Firefox 78).
== What happens ==
After playing for a while (anything from just a few seconds to a couple of minutes), the video stops and is replaced by a service-specific error message, such as error #3000 (in case of Twitch) or (Youtube). Even when playing, the video also flickers green. After reloading the tab, the video again plays for a few seconds before the error message reappears.
== Other info ==
A fix is apparently already in the works upstream .
*  https://mastransky.wordpress.com/2020/06/03/firefox-on-fedora-finally-gets-va-api-on-wayland/
*  https://bugzilla.mozilla.org/show_bug.cgi?id=1645671
Since upgrading to 20.04 and switching to Wayland, Gnome terminal occasionally crashes. I interpret the corresponding logs to mean that it’s actually Wayland that fails to do something in the background, which then takes down Gnome terminal:
touko 08 11:35:16 saegusa gnome-shell: WL: compositor bug: The compositor tried to use an object from one client in a 'wl_pointer.enter' for a different client.
touko 08 11:35:16 saegusa gnome-shell: WL: error in client communication (pid 11639)
touko 08 11:35:16 saegusa gnome-terminal-: Error reading events from display: Katkennut putki
touko 08 11:35:16 saegusa systemd: vte-spawn-bbca1723-5987-4ccf-98cb-3389ad05641e.scope: Succeeded.
touko 08 11:35:16 saegusa systemd: vte-spawn-fbe02208-95df-4cf4-bfbe-fffc71d6bc7e.scope: Succeeded.
touko 08 11:35:16 saegusa systemd: gnome-terminal-server.service: Main process exited, code=exited, status=1/FAILURE
touko 08 11:35:16 saegusa systemd: gnome-terminal-server.service: Failed with result 'exit-code'.
I have yet to nail down the precise circumstances, as this has (so far) been somewhat rare, having occurred perhaps once or twice a week.
Since the log mentions pointer, I should perhaps mention that I’ve set `org.gnome.desktop.wm.preferences` > `focus-mode` to `mouse`. Gnome terminal also exhibits other misbehaviour wrt. to this, occasionally refusing to get focus, or alternatively losing the focus, despite mouse cursor being over the terminal window.
Oh and I’m using Wayland, in case it matters here. Haven’t yet tried whether Xorg is similarly affected.
Alright, from my brief testing it would seem this does not reproduce under Wayland.
My recipe above appears to be quite sensitive to details: I have a test user with a clean desktop (with little more customization apart from the extension), and there the recipe works just as written. On the other hand, with my main user account it doesn’t. To clarify: while the steps listed above fail to reproduce the issue with my main account, my main account does manifest the issue too; just not with those exact steps.
My main account starts up the Signal desktop client, Nextcloud client and some other stuff upon login, but so far I haven’t found which of those (if any) causes this difference.
I was, however, able to reproduce the ”see-through hole” effect under both accounts: instead of maximizing Gnome terminal (in step 3), I tile it to cover the left half of my screen, then start up Chrome/Firefox, tile itover the terminal window (i.e. to also cover the left half of the screen), before turning the display off and on again. Firefox then also manifests the hole, as does Gnome terminal when brought back to foreground from below. (Chrome does not manifest the hole, but then again Chrome has always appeared oblivious to the extension here.)
I should mention that I’m leaving the display off for about 4-5 seconds before turning it back on again. I’m not sure if that makes any difference, I’m just doing to to be sure that the ”I’m off” signal has time to propagate back to the system.
I’ve only used Xorg too, but I may be able to try reproducing it under Wayland over the weekend.