Hadn't thought about doing this, but I just took a DVD burned in our Humax and popped into our iBook.
The disc showed up in the finder... with a folder labeled Video_TS and a bunch of cryptically named docs inside. Double-clicking any of them results in an error message or rather a prompt indicating that it doesn't know which application to play the file!
So, it looks to be more complicated than expected. Then I read a previous post that mentioned DVD Player. I launched it. And got an oddball message about needing to set the Region! With a pull down menu of choices (Region 1, Region 2, etc.--realy helpful Apple!) and a comment, a warning, a threat actually that one can only do this 5 times! Bizarre!
Then I clicked the Select Region button figuring it would give me a world map or something... instead, it happily reported Region set (wait! I didn't choose one) and launched itself, with the TiVo DVD screen coming up full screen! Amazing!
And then I selected a movie to play and it did so! Alas, there was no easy way to returning to the dock (which had been made invisible). I tried the command key for hiding/showing dock, no go, tried escape, but that simply restarted the movie, tried space bar (in other words all the old Mac tricks). Finally had to quit the Player.
There must be a way of doing a background play or small window play, I'll have to check that out. (Ah, discovered that the menu bar becomes visible when one move the pointer--invisible-- to the top of the screen, an old trick I had forgotten about. And sure enough, one can exit full screen mode.)
Of course, ultimately this is not something I plan on doing much if at all. I'd rather watch the movie on a TV!