This isn't really related to webhosting, but you guy know something about payment processors, so here is my plan:
I have a website with movies.
A visitor that wants to view one has to pay, let's say, $10.
User clicks a link, enters his credit card information, and submits the form.
The information is being verrified, and the visitor is being billed $10. Then the user gets to a page where he can watch the movie.

I also have an other plan: Same a above, but visitor pays a fixed monthly fee, get's a username and password, and can view as much movies as he wants.

Anyone has any idea on how to do this?

it wouldnt be that hard to do. Im sure anyone good in php or any other scripting language out there could set somthing up for you. If you are looking to do it on your own just figure out how your merchant works or whatever payment system you use works and after that coding one would just be a matter of time. If you want someone to do it for you i can set you up with someone just PM me