Not that I think downloading is the right target for the RIAA (they should embrace the technology like iTunes) but I think this strategy could work, and here’s why. By targeting the suppliers of free music, they attack the only group that has NOTHING to gain from the risk. Putting your MP3’s up on the net has exactly zero benefit to you, but you expose yourself to risk. Before this, the risk of getting in trouble was also zero, so nobody thought twice about opening their collection to the net. In addition, they do not have to prove you have an illegal copy, they only need to prove that you made illegal copies available, and that isn’t too difficult.
As a supplier of these files, the entirety of the internet must be able to find your PC and request the file from it. Perhaps there are anonymizers out there to protect you, but still, why bother? You will be earning $0.00 by going through all this trouble, and the only beneficiaries are a bunch of random internet users who won’t get in trouble.
Targeting the downloaders is a losing proposition, they have something to gain from taking risk, namely the free music. You’d have to raise the risk to outrageous levels to make a dent in that population.
It may be that the risk is considered negligible by the population and it won’t work, but I think this is their best idea so far.