Hello.. nowhere in any of Tivo's information on this feature does it explain the difference between "renting" and "buying" a movie when downloaded on Amazon Unbox. I'm Guessing it Probably means that movies you rent will automatically be deleted from your Now Playing list after a certain amt of days, while movies you buy stay for good. But I can find nothing to confirm my suspicions, and if so, how many days do you get to watch the movie when you rent it. Anyone?? Thanks in advance!!