Monetarize download links

My problem is the following: I have a porn tube that allows video downloads. I want to monetarize those. I tried to write a simple mod_rewrite rule to use my adult.xyz link whenever "download.php" gets opened, but this method will cause an endless loop.

How do I get it working? Users should get the adult.xyz intersitial and then be redirected to the download.

Is adult.xyz don't have a full page script (auto shortened links) that you can paste within your body tag? I think all url shorteners have this feature.