Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Yup, you sure can. Just open up the Window, and underneath the playhead you'll see two little hash marks. Adjust those to encompass the audio you want, then go to Edit>Extract Tracks>Sound Track. A new little window saying Untitled.mov or Untitled.mpeg or what have you will pop up. The go to File>Export and export it as either .WAV or AIFF. Then open it in iTunes, and Convert Selection to MP3. I'm sure there's an easier way, but that's all I could figure out.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.