Q: I have an iphone but I want to purchase moves from itune and watch on my PC laptop.  Itunes won't let me - why not?

Hi montefalco,

Thank you for using Apple Support Communities.

If you are unable to watch a movie on your PC that was purchased on your iPhone, my first thought is that your PC might not be authorized. Take a look at this article for additional information:

Authorize your computer in iTunes - Apple Support

Cheers,

Jeff D.