Have a look at this--http://videomaker.com/community/forums/topic/audio-sync-1
A lot us us are having the same problem. It really is a pain. I'm trying something new right now - capturing the audio from the Zoom in real time to my computer, not just copying the .wav file. Since the Zoom's internal clock will also be used for playback, it may just work. I don't like the idea of going back to analog, and the length of time it takes to recapture, but if it works it'll beat having to resync every few minutes.
I have a ZOOM H4 digital audio recorder. It will save in any format you want. I was videotaping an event using standard MiniDV camcorders. I also set up the ZOOM H4 on a tripod for audio recording. Much to my chagrin I was not able to synch the audio recorded on the ZOOM H4 (saved .wav) with the audio/video tape. I saved the Audio/Video onto my hard drive as usual (.avi) and I used Adobe Premier Pro. I saved the .wav from recorded on the ZOOM H4. I synched the tracks at the beginning. Slowly the H4 audio loses synch - so much so that I had to re-synch it about every 3 or 4 minutes. I found this pretty strange since I thought a .wav file was a .wav file and figured that there shouldn't be any difference in timing on them since all the files are digital. Can anybody explain to me what's going on here. I tried emailing ZOOM and got an answer back in broken English. Something to the effect of the "internal clock" on the ZOOM H4 being different than that used by DV camcorders (???) Using the ZOOM H4 seemed like an ideal way to capture somebetter audio than that recorded by the mics on the camcorder...and you could simply mix them to your liking in Audition (or any other Audio Processing application). Not so! But I don't understand why.
Any help in understanding this phenomenon would be appreciated.