On documented fact that is being left out of this discussion, the more convienent something becomes,the more impulsive the purchases become. When you have to go to the grocery store that is several miles and has long lines for milk, you are more likely to plan ahead on your shopping. But when the convienent store opens at the end of your street, you stop planning your purchases as much. You also grab an individual sized bag of chips and an ice cream bar with the milk. Convienence made you pay more, plan less, and buy stuff you didn't need.

It doesn't get more convienent than buying a movie with a remote. But I don't see a lot of planning going into the purchase. I think Alan is right, it's a very spontaneous transaction. Especially considering the precedence that iTunes and Vudu have established.