Are you paying attention, MPAA and RIAA?
Monty Python started a YouTube channel with tons of their sketches streaming for free. The included links to their DVDs at Amazon. The result was a whopping 23,000% increase in sales.
A controlled release of free material keeps people from resorting to piracy and keeps them in your controlled ecosphere, which can include, yes, ways for fans to give you money. But when you’re a bunch of pricks, people go to The Pirate Bay and think of you as the enemy, and then you don’t get any money. Take notes, you idiots.