Link stealing...
 

Say you post a movie clip on your forum, but then someone else decides to paste that link on their forum, now their downloading off your site is there anyway to prevent such a thing? like if they wanted to download it, they would have to be on my website only?

Checking the Referer would be the only possibility IMHO.

The two best ways are probobly:

-Upload the movies to your forum database, and set permissions so guests can't download them.

-Search google for a "hotlink protection" script.

"Hotlink Protection" == Referer Check :)

hmm will give it a shot thanks

According msdn knowledge base (I read a while back when I tried to prevent this), they said webserver won't check the referer on media files. In another word, some site asks for those files, your server will fetch those files.

That's a pretty good solution. But with video files, which tend to be large, perhaps store your attachments in the filesystem.