Yeah, I hadn't done anything with DVD. Of course you can use applescript to control the DVD player, so that's an option.
I'm sure you can play a DVD, though...
[Edit: It looks remarkably similar to just playing a quicktime video. Here's link to a tutorial on how to applescript the DVD player. I presume you can set an NSMovieView Cocoa control to receive the video, just like you can a quicktime video stream]