The big music companies don't seem to have recognized yet that they fail to have control over one crucial aspect of the Internet - distribution. Knocking out Napster in the courts and stepping on any other upstart MP3 Website is the music industry's way of trying to get a grip on distribution. Technical measures like special encoding that allows one play only, or fails to play pirate versions, are further admirable methods of attempting to protect copyright and at the same time get a stranglehold on distribution. In fact the biggest commercial benefit of having music streamed rather than providing it as an MP3 file is that the provider remains in control, the user can only listen when attached by a long tenuous wire or paid-for wireless connection. But all these measures are doomed to failure.
Computers are superb recording devices.
Whatever I see or hear on my computer I can record. Any kind of technical measures to stop me are mere complications. All I need is plenty of space on my hard drive. Even if I bought streaming music, I'd only have to buy it once. Actually big business did recognize this weakness some time ago, which is why a lot of browser software is getting more restrictive rather than less.