The entertainment industry sees services like Napster as the death of its business, and it's using every technical and legal means possible to prevail against them. They want to implement widespread copy prevention of digital files, so that people can view or listen to content on their computer but can't copy or distribute it. Abstractly, it is an impossible task.
Bits are inherently copyable, easily and repeatedly.
This is a natural law of the digital world, and makes copying on the Internet different from copying Rolex watches or Louis Vuitton luggage. What the entertainment industry is trying to do is to use technology to contradict that natural law. They want a practical way to make copying hard enough to save their existing business. But they are doomed to fail. Any security measure will work against the average users, who are at the mercy of their software.