@A4000_Mad
There is nothing you can do for Moovid since it doesn't support external codecs. SoftCinema and AMP2 supports some of the xanim PPC codecs for linux. There is a website where you can download them but i don't have the URL. You will find it if you search google with the right keywords.
Have a look at ffmpeg too. It's a video converter available for all Amiga OSes.
Is there a PPC version of Riva?
No.