There are a lot of questions about editing video that comes out of the 5D mk ii. I'd like to get a whole section put up in the wiki about it (and there's some good stuff there now, but it isn't very complete.
Stephen Alvarez has done a series of posts on dealing with the 5D2. The first ones were covered here.
Just now, he also just posted yet another article on syncing the sound from a 5D mk ii. Which has some real good information in it.
Stephen is a great 5D mk ii resource!