Their system is changing quite rapidly at the moment.
They used to give rewards to those who uploaded massive amounts of popular data (guess which kind of files were popular?):
(
not my account - I don't have one and never did)
But they've stopped that since the court judgements against them.
I believe that people tend to upload files with names that give no indication of what is in the files, then index them on another website, to get around the issue of copyrighted files being taken down. Some files use passwords too, so that it would be very hard for anyone to expect RS to check what was in them.
Ultimately, they were making considerable amounts of money out of other people's content, since they motivated power-users to upload stuff with the prizes, and then you could effectively only download larger files by paying for an account with them.
This system is effectively gone now, and we're in the process of seeing RS losing a large proportion of their users. Why go to the trouble of providing the content (even if it wasn't yours in the first place) if you no longer get any reward for doing so?