I had a problem as well, where the application crashed on me:
http://forums.cnet.com/5208-21573_102-0.html?threadID=374403&tag=forums06;forum-threads

But the issue, as I stated in my post, was that I had a bad disk. The crash occurred in the preparing disk stage, but that happens right before it tells you that it is multiplexing (essentially compressing the video to be DVD format).

Try it with another disk. And the folks at Apple tell me that DVD Minus R is going to work a lot better than Plus R.