To play a DVD, you need to be running X in 16-bit color mode. With the DVD in the drive, type:
# ac3dec /tmp/audio& mpeg2dec /tmp/video& oms
If all has gone well, some text should fly by, followed by it asking you if you want it to look up the name of the disk in the DVDDB. It is safe to say yes. Then, the oms panel should pop up. Click the play button and the video window should appear and begin playing.