Q: Why do I sometimes see on the file sharing sites or postings that a certain game (let's say, Diablo 3, as of June 2011) is already out in beta or something? I downloaded the file, but it's got a RAR password that no one seem to know.
A: You got a decoy or "bait". If you read the README file that came with the decoy, you'll see that you're requested to go to a certain website (probably porn or warez) and watch a video or something and if you watch enough of it you will find the password. In reality, there is no password. The file has nothing useful in it. Its sole purpose is to drive traffic to that website and make money for the website owner that way.
Originally this used to be a scavenger hunt, as the jokers would leave one clue after another leading you on a wild goose chase, and finally leave you with a "Ha-ha, got you!" message. It's no different than people uploading gay porn to P2P under tantalizing titles like "Natalie Portman's secret sex video!" (There is no such thing. Get over it!) Basically it's a joke at your expense.
When internet advertising came along people started doing it intentionally to drive up traffic, or worse, install a bunch of crap spyware, toolbars, and other apps that gets the distributor a small amount per install, no questions asked. So they put the stuff in bait packages and you... took the bait.
See below for one such example.
