Check out this preview grab of a new movie player for OS4:
Click for previewIts being written by the guy behind RiVA, but its not based on RiVA as that is 68k assembler. Its primarily designed for MPEG1/2, VideoCD, SVCD, and DVD playback but apparently more formats may be supported as well.
Not only that, but I hear AmiDog is waiting on the prerelease and intends to port some of his software, too, so it looks like we'll get Moovid, DVPlayer and AmiDogs Movie Player :-D