I'd ask them how to fix it.
But it is worth noting that lip sync is a well discussed area with too many discussions about using video editors to fix that.
I'll note that as well as VLC PLAYER has a setting to adjust for bad sync.
I have transferred some videotape to avi using AVS Video Recorder. When playing back video I notice that the audio is about a half second ahead of the video. This can be distracting on playback. I then convert AVI to M4V (to play on Iphone) using AVS Video Converter. There is no change in video/audio sync.
Is there adjustments I could make to sync the video and audio so it plays both in time?