A great majority of those "extras" are pretty dry. Especially the directors commentary tracks. I actually put on FOTR with the commentary when I was painting minis one day and this is an example of the 4 hours of commentary.
Director Chick 1: I remember that guy...he was sick the day we filmed this scene.
Peter Jackson: Was he?
Director Chick 2: Yea, I think he had a cold.
Peter Jackson: Hmm...
[5 minutes of movie dialogue]
Director Chick 1: That was nice costume.
etc etc
The extra I wish EVERY movie came with was Spidermans pop-up-video style factoids while the movie played.
DS