Did you consider that many of these spammers may use dynamic ip's? Meaning your blocking of them might work for that day, but the next day, somebody who has adopted that ip ends up being blocked by a large % of p2p users. Not everybody uses a static ip.

If you're concerned about spammers then filter them out. The wmv & jpg results can be filtered out. Only compromise is if you particularly want to download something in that format. lol