Alex Kac used Apple's TomeViewer utility (as far as I know, currently only available to members of Apple's developer program) to extract the ATI MPEG Accelerator file from the Mac OS 7.6.1 Installer files and install it on his Xclaim VR equipped Mac. He writes: "Guess what! It accelerates MPEG files very
well - although it plays it a bit fast."
b. Speaking of MPEG, Robert Guerra spotted the mention of a new MPEG3 player on the MPEG-3 Macintosh page. It's called MacAmp. According to MacAmp's ReadMe file: "MacAmp (Macintosh Audio Mpeg Player) is an MPEG audio decoder. It works with both MPEG1 and MPEG2 audio streams (except for the multichannel extensions defined in MPEG2), layer3 only for now."
AudioActive and MacPlay3 are the two other alternatives to MacAmp.