an you describe the changes you make to make vaapi/vdpau work? We could put them in the manual.
The solution Glitterball3 provided is quite creative and I never would have thought of it. I tried it starting with the older_distro appimage on my newer system and did not succeed so I think it would take a more educated user to implement it. So probably should not put it in the manual. But just knowing how to Extract the AppImage files is so useful so thank you Glitterball3.
What I did:
Extract the files from the AppImage:
/path-to-appimage/CinGG-20211231-x86_64.AppImage --appimage-extractRun CIN
/path-to-appimage/squashfs-root/usr/bin/cinUnder performance tab in Preferences, set Use HW Device to vaapi. Click Apply.
Quit and restart CIN
/path-to-appimage/squashfs-root/usr/bin/cin