Code's to call upon url links in the db that user can't see

[Replicators]

The way i wanna do things on my forum is to have people upload html files as attachments that open automatically once they download it by use of mimetype. And inside the html they have links to files, but links would not be inside the html file. It would be in the forums database instead, allowing the link source to be hidden from user period. Now i know one of them ways to do that is to have the database act like a mirror for the file, in which to the user it would seem they are getting the file directly from your site. Is there a way to accomplish this without using the bandwidth of your forum server? Please anyone say if this is usefull too, as i could use something like this.

Also a person would need to be logged in and have the correct permissions to fetch the certain file. All i want to know is is this possible? And if so, could someone spend the time to build it?