Originally Posted by AutumnBH

Set a cookie that contains a number. Each view of a movie page increments the counter by 1. When you reach max views per page, either a) redirect to the signup page or b) display a message with a greyed out flash player and a message prompting the surfer to signup. If you wanted to do (b) then you could use a WP custom field to hold that html.

Put the cookie increment counter / redirect in header.php of course.