http://www.originaltrilogy.com/forum/messageview.cfm?catid=9&threadid=1389&STARTPAGE=2
Minor differences in the number of frames in a shot can add up to a noticeable de-sync over the length of the film. If you were to collect all the different soundtracks, you would also need some form of reference to the video as well, or some way of ensuring the audio can be synced to different video source.