The T&C used to specify that rented “movies” could not be moved between devices. The term “movies” has been replaced with “content” when it comes to rentals, thus including everything one can rent from iTunes, which is, more or less TV shows and movies.
The screenshot below is the T&C notification, complete with the change stipulated at the top (which is Apple’s policies for making such changes), on an iPhone.
iTunes T&C Change