I had the same problem for some videos but not for all of them, apparently independent from the used codecs and independent from the video duration.
After a few hours trying to understand the reason, I discovered that the problematic files had a sound frequency which is no multiple of 11025Hz.
For instance, videos with 44.1kHz had no synchronisation problem in contrast to video with 48kHz!
After conversion (using for instance sharewares available in internet) the video and sound were synchronised!
I should have thought about it earlier, since I had the same problem a few years ago with a poor arcsoft Software…
Regards,
David.
