I found this very interesting:

Last year, we wrote about Monty Python's decision to put all its content online for free hoping that would drive people to buy more of its scarce goods -- such as DVDs. And, as a bunch of you have submitted, it appears to have worked wonders. Monty Pyton's DVD sales jumped an astounding 23,000% and are now the number 2 best selling item in the Movies & TV category on Amazon.com. Who was it that said "you can't compete with free" again?

Taken from here

-MG