So you’re watching Lady Terminator but you don’t have time to finish it. You’re going to be busy until tomorrow night, and your movie is only rented for 24 hours! It’ll be long deleted by the time you get back. What the hell? Well, here’s what you do: hit pause. That’s it. When you come back to it a day from now (or more; no outer limit has been established) and hit a button, it will prompt you to either delete the movie or finish it. Sweet! After all, you did rent the whole movie.
Apparently, as long as you start the movie during your allotted 24-hour period, you are allowed to finish the sucker no matter what, though testing needs to be done to determine how long before it really expires, whether you could maybe rewind it to the beginning again and again, and so on. Ah, high-definition on-demand cinema: the final frontier. I suppose we could ask Apple to explain the whole thing, but that’s not nearly as fun. Let the experiments begin!
Extending iTunes rental times [Macworld]