Ive done this with mac the ripper to remove the protection on a dvd. Then use Mpeg Stream clip with apples mpeg 2 component to extract the videos sound to Aiff. That method costs about twenty bucks for the mpeg2 component. You could use handbrake to rip to a video and then use mpeg stream clip to rip the audio out. I would not prefer this way if audio quality is what your trying to achieve the best sound quality since handbrake compresses the audio and if you are trying to make a mp3/aac file out of it, itunes will compress again.