He also talks about a lot of other stuff which is pretty damn mind-blowing.
Folks that haven't watched this talk... you should. It really got me thinking in new ways. There's a reason why von Ahn won a MacArthur ("Genius") Grant for his Human Computation work.
Hmm. It would be nice if someone released a benevolent trojan that basically informed everybody that infinite porno is available via bittorrent. All in all, it would be nice to close down the manufacturing end of that business...
He talks about how spammers use porn sites to correctly input captchas back in July of 2006.