You should be able to on a 040@25mhz or better. I have played MPEG 2 files without issue though not an actual DVD.
Not likely (040@25MHz, I mean), at least not at the proper resolution/framerate. First of all, the resolution of DVD rules out playback on most m68K amigas. A PAL 720x576 @25fps using (where supported) a packed 24-bit RGB framebuffer needs 29.7MB/s VRAM write speed to keep up. On a 32-bit framebuffer that increases to 39.55 MB/s.
So, even assuming you go for 16-bit RGB565, you are talking about 19MB/s which is more than you can get transferring data to the BVision using an unrolled move16 loop on the 68040 (the 68060, however, can move data a bit faster than the 040). Every other Gfx card available for the A1200 has a slower CPU -> VRAM path than the BVision/GRexx does, especially Mediator attached cards.
You'd literally use up virtually all your CPU power just updating the display, without even worrying about decoding and CPU hungry disk IO if you are using a non-DMA DVD drive.
I've played back (non-CSS) MPEG2 streams from hard disk on the PPC to BVision and that's worked reasonably well, albeit at a slightly lower resolution than standard DVD. Playback of actual DVD disks read via DMA would seem reasonable on that premise.
