Extract sound from video clip

Looks like a program called Action Script Viewer (ASV) is mentioned as a possible solution:
http://idtech.blogspot.com/2005/02/flv-to-other-revisited.html
To do that, I would need to get not only Action Script Viewer, but also Flash Pro. The other way suggested, using Audacity does not sound like a workable method either. What is Wave Out Mix? I was unable to find it in Audacity's window or in any of the menus. Are they suggesting that the microphone pick up the sound from the speakers? That does not work well. The volume is too low.
 
QuickTime can handle .flv files if you give it the right codec. What is the advantage of converting the file to .mp4? Extracting from a video file is possible with QuickTime Pro, not plain QuickTime.
 
Back
Top