How can I get my iTunes rented movie onto another computer? My father has rented a move on iTunes, but on his old computer (which can't cope and crashes when he tries to play it). He's now on a newer computer, and logged into iTunes with the same account, but we can't find the rented movie.
I can confirm that the following works:


I downloaded a movie on my pc-laptop 
I moved it via my network share, added it to the library on my macbook
It was visible as rented there but could not be watched (authorized to another computer) 
Then I unauthorized the computer I downloaded it on and it worked on my macbook