An NYT story on classical and rock guitar players posting versions of 17th century chamber piece
Pachelbel’s Canon to YouTube demonstrates the value of public domain materials and web-based collaboration:

This process of influence, imitation and inspiration may bedevil the those who despair at the future of copyright but is heartening to connoisseurs of classical music. Peter Robles, a composer who also manages classical musicians, points out that the process of online dissemination — players watching one another’s videos, recording their own — multiplies the channels by which musical innovation has always circulated. Baroque music, after all, was meant to be performed and enjoyed in private rooms, at close range, where others could observe the musicians’ technique. “That’s how people learned how to play Bach,” Mr. Robles said. “The music wasn’t written down. You just picked it up from other musicians.”

Now if only YouTube facilitated CC licensing of contributed videos (like blip.tv) some of those modern reworkings of Pachelbel’s Canon would be legally available for other forms of remix, e.g., sampling (mp3).