Yes, it can be done with this.  You would just enter the hidden download page URL in your Market Theme settings administration area.

That way, when the customer is directed back to your website from Paypal — they will be directed to the download page where they can get their movie.  Just make sure to set your return URL as described in the Market Theme "readme.html" file included in your download package.  The section on "inventory control" contains the return link you need to put into Paypal.  That return link has code that will read your "thank you" page URL from the settings area, and then automatically redirect.

If you want to use something more dynamic, you can also integrate Market Theme with e-junkie.com.  (e-junkie.com accounts allow you to provide download links that expire after a certain amount of time.)  This would make things more secure and would prevent your download page link from being shared.

It's not required, but available.

Although, you can always just change your download link location every once in awhile too.  That'll work as well.