The ISPs are cutting deals for the legal downloading of music from different labels. That’s how come this will work. The more music sold, the more they make. I think they are using this as practice for video as well. Soon, they will also police video downloads just watch. All they have to do is prove they can spot pirates and the money starts a rollin’. If they spank their subscibers it forces them to either stop illegal downloads or else start buying legal music. In this way the ISP is being “paid” to make their customers tow the line.
it is clever as it skirts the legal system completely and is efficient and cheap. I bet the contracts for new subscribers has plenty of warnings and also they have the right to drop your service if they feel you are doing something unlawful.
I always thought it was funny, thhat the people were getting busted for downloading Brittany Spears or Jacksons Thriller. While at the same time Comcast was HOSTING terabytes of warez on their news server!! Not once did I hear a threat from the RIAA or the MPAA for Comcast to quit hosting movies and music and warez- never. 
Then, all of a sudden, they started backing away from usenet and finally dumped it all together. Now, they are wearing the white hat i guess.
If you start DL’ing gigabytes of encrypted files they will simply flag you as a pirate or worse yet- a terrorist or a child pornogrpher LOL. They don’t have to prove a darn thing. It is their right to kick you off the node for whatever reason they want. All they have to do is look at the traffic, where it originates etc. it doesn’t take a brain surgeon to know when someone is pirating. It also is not necessary to prove it. Just scare a few and get it in the media.