I've been fighting this same problem for quite a while, and all the solutions I've seen center around stripping the audio from video and converting to .wav file using VirtualDub product, then re-interleaving the wave file with the video. I could never get these solutions to work.

Since I only cared about watching the video without the audio getting out of sync the farther it got into the show (and the more commercials which were cut out), I took a different approach and started looking for a movie viewer which would allow me to adjust the audio to match the video. I finally found the Zoom player at www.inmatrix.com which does exactly that.

Unfortunately the feature isn't on the standard control panel, so you have to learn how to add it or, like me, just use the keyboard shortcut by holding down the shift key and pressing the + or - keys on the numerical pad.

Hope this helps! G.