Copyright has turned into a double edged sword. Its purpose is to protect people and corporations from having their work duplicated without compensation. Eventually, this work is supposed to pass into the public domain where it becomes everyone's property. However, these days the bulk of copyrights are controlled by multinational corporations who are in no mood to let assets slip from their control.
The last copyright law in the U.S. prevents anything copyrighted after 1923 and still under copyright at the time the law was passed from going into the public domain until 2023. Larry Lessig is a lawyer and university professor who challenged the constitutionality of the law in front of the U.S. Supreme Court. Unfortunately, the court ruled against him.
Much as they'd like to, governments and corporations can't stop the world from changing and culture has the nasty habit of evolving without needing anyone's official permission. Below is a 20 minute video of Lessig discussing why governments and corporations are behind the times and how mash-ups are a vibrant form of contemporary culture. Lessig is still looking for ways to make the copyright laws more balanced as he fears that in their current state they will restrict the creation of culture and make us intellectually poorer.
This video is one of many resulting from the TED conferences. The topics are wide ranging and some are scientifically complex, but the speakers generally are good at explaining things to a lay audience and there's lots of provocative material here.