I consider myself an introvert, but people tell me I never shut up. So uhh... somewhere in between? :) Not sure why it took the form of movies, but most people do have trouble ceasing thought, as I'm sure you experienced.
Yeah, if I was isolated I would use it to my advantage and meditate. Perhaps I would exit enlightened :)
One thing I've always been really curious about is how an experienced meditator like a Buddhist monk would deal with forced solitary confinement. I think they would probably do much better than the average, untrained person. Now that would be a really interesting experiment.