I’ve not yet found a solution to this issue and the Raspberry Pi forum hasn’t been able to help.
I made a very similar post back at the end of May this year. I fixed the issue, short term, by getting Gemini Deep Research to create this installation recipe recommending the use of X11: Enabling H265 Hardware-Accelerated Video Playback with python-vlc on Raspberry Pi CM5 (Linux 6.12.25 Bookworm, X11) - Google Docs
Here I’m using vlc which does what I want, however I have to provide it (vlc) with the X11 window ID of the Qt frame within which I want to play the video:
self.player.set_xwindow(self.video_frame.winId())
I’ve not yet found the equivalent in Wayland!
Would be super pleased if anyone could assist me with my move to Wayland.