OS: Fedora Linux 43
   Firefox 147.0.1 (also tested Firefox Flatpak)
   Display server: Wayland and X11 (both tested)
   Hardware acceleration: on and off (tested)
   Media Source Extensions: enabled (disabling MSE triggers an “unsupported device” error)

   BBC News videos play correctly in Chromium-based browsers (Brave, Vivaldi)
   Videos play correctly in mpv/VLC
   Other video sites (e.g., YouTube) play correctly in Firefox

   Disabling hardware acceleration
   Disabling VA-API
   Disabling WebRender
   Disabling RDD sandbox
   Running Firefox under X11
   Using the Firefox Flatpak build

They play for a couple of seconds, then the panel they are playing in goes black. They used to work a month or two ago. Videos play fine in YouTube. They also play fine in apps like VideoPlayer and VLC. They play fine in Chromium based browsers Opera, Brave and Vivaldi. My graphics card requires switching acceleration off. I can’t find a switch for that in Firefox. Problem Videos start playing, then after a few seconds the video panel turns black. Audio may continue. Refreshing does not help. Environment OS: Fedora Linux 43 Firefox 147.0.1 (also tested Firefox Flatpak) Display server: Wayland and X11 (both tested) Hardware acceleration: on and off (tested) Media Source Extensions: enabled (disabling MSE triggers an “unsupported device” error) What works BBC News videos play correctly in Chromium-based browsers (Brave, Vivaldi) Videos play correctly in mpv/VLC Other video sites (e.g., YouTube) play correctly in Firefox What I’ve tried in Firefox Disabling hardware acceleration Disabling VA-API Disabling WebRender Disabling RDD sandbox Running Firefox under X11 Using the Firefox Flatpak build None of these measures help. This suggests the issue is related to Firefox’s interaction with BBC’s player on Linux. Has anyone else seen this, or is there a known workaround?