So, I used to use the -dumpaudio switch in mplayer to get audio extracted from random videos, but now that seems to do not much of anything. I found this site
which had a great explanation of how to get it done a different way, but was a bit out of date. The newer version is found below:
mplayer -vo null -ao pcm:file=audio_file_name.wav video_file_name.avi
Hope that helps you as much as it did me.