I only had some movies out of sync. not all of them.
But all little devices or converting videos can do this. iPods also have this video-audio lag. I convert some to play on my netbook (no cd/dvd drive) and one had the lag. All different formats. Not sure why or how come it happens, but it does. And it’s not necessarily the same movie, although it can be.
[note: I watch one video at a time on one device… my coworkers have their own dvd’s to convert, although haven’t for a while, the novelty wore off I guess]