Is there a program that, with using a video file, the capturing program I use turns it into an MPEG file or something like that, you can convert the sound on it into a normal sound file? I hope I've explained myself, I want to convert the sound on a video file into a sound file.

Help would be appreciated

Download Format Factory.

Use SUPER, it can handle pretty much any conversion.

http://www.erightsoft.com/SUPER.html

The download process is annoying, and it took me 15 mins to figure out, so here:
1. Scroll all the way down and click "Start Downloading SUPER ©"
2. Scroll down again and click "download and use"
3. Scroll down... yet again... and click "Download SUPER © setup file"