zombie84 said:

Can you just sync it the way editors do when there is no slate clap or time-code-slate? You basically just find something in the scene that substitutes for a slate clap. So if something gets banged, something drops, something explodes, any sort of clear picture-sound correspondance that you can pin down to a frame or two. It'd be a lot of work, but if you basically do a check like this every five or ten minutes it could be a way to make sure nothing is out of sync.

This is how you pretty much have to do it if you're syncing to video and not the GOUT audio. Don't try to sync voices to lips, that's too damn hard.