I ran into a problem trying to watch DVDs on my Beige G3MT. I tried using VLC (it sucks) then I read where someone used a program called Pacifist and used it to open the OS X installer files and installed the DVD player from OS X.
I am using OS X 10.2.8 and I did the same thing using pacifist to open the OS X installer files on the install disk of OS X and I'm here to tell you it works. Great DVD play, no choppyness just excellent playback. You can get pacifist from verisontracker.com.
You do need to have the ATI 16meg PCI video card or better installed in your machine