1) load the AVI with VirtualDub (you'll receive a warning about auio)
2) set Audio___Full processing Mode.
3) Do File___Save WAV.
You'll make a huge uncompressed WAV file (10.1 MB x length, in minutes)
Now load that uncompressed WAV file as 'audio input' in TMPGenc.
If you aldeady encoded the MPEG and you don't want to throw it away, simply compress that uncompressed WAV to MP2 with HeadAC3he, then multiplex it (File ____ MPEG Tools ____ Multiplex) to the video part of from the old 'unsync' movie (type: MPEG2 SuperVideoCD).
Yes, BeSweet is more powerful than HeadAC3ha but has many switches to modify an often gets you a bad result...ood for you it works, now.
But I insist: the link was talking about is http://forums.afterdawn.com/thread_view.cfm/129217 and it's working!