Well,

I tested everything I could, I checked that everything was set up correctly.

I rebooted many times.

And no video (and I tried a lot) is being played on my PowerMac G5 2.7 Ghz with a Radeon 9650 (MPlayer works without trouble).

Any idea? Is it my system which is unsupported?

Wayfarer 1.12 (17.04.2021)
cgxvideo.library (in MOSSYS:Libs and also in Libs:) 43.18 (16/04/2021)

I'm giving up for the moment, I spent a lot of time on this and couldn't play anything.