Right.. go to renderosity and you'll have to sign up for an account.  Go to download a freebie, and a lot of the links in there freebie section lead over here to sharecg, which would then ask you to sign up for yet another account, etc, ad infinitum.

Like I said, yes, requiriing people to sign up for an account will help lessen the abuse, provided you throw in a lot of bot checks and other security measures to go with it.

But lets look at the overall effect that has on your community.  Some guy follows a link here from renderosity, discovers he has to sign up for an account and does.  Then he has to fill in a security check to prove he isn't a bot.  Then he downloads his file, and at the end of all that his thought is "damn, what a pain in the butt for one file, hope it was worth it". 

Whereas that same guy shows up here at sharecg following a renderosity link and downloads his file.  Since he's done and the webpage is already open, he browses around a bit, sees all the great stuff there is here on share cg, and then gets interested.  Pretty soon he signs up, and realzing he can host stuff here for free that people dont' have to jump through hoops to download, becomes a content provider and active member of the community.

Odds are good the second never would have happened if the first part of the process had required the account information and the bot checks and all the other crap that is going to be need to make a pay per download system work.

The whole point for many of us hosting our freebies here is that you can download them without all that extraneous nonsense.  Our focus is on the clients, the folks actually downloading and using the stuff.

That is where I think sharecg's focus must remain if it's going to continue to be successful, I think if they start burdening their new vistors with a lot of extra hoopla and security checks they are going to have a lot of new users say "Nope, just isn't worth the hassle", and go elsewhere.

Make your clients happy and they come back, indeed they bring others with them.  Irritate them and they go elsewhere, it's as simple as that.  So while the account info/bot check/blood sample et all approach would work in weeding out the scammers, I think it would eventually kill the revenue sharing concept in another way, there just wouldn't be much revenue to share.