The Long Tail

Just what is the long tail ?
The long tail is that elusive marketing component that says the big money is in letting something ride for a time (like an investment). The big money isn't in Britney Spears, it lies in the long tail of misspelled and uncharacteristic keywords. What's this got to do with a blogger or a community developer ?
Consider Google, they are in the heated battle of their lives. They have all the MPAA and RIAA execs at their door begging them not to go forward. Yet they will. Why?
Consider the mix differential. I can take a video off youtube, that has been designated Public Domain and do with it whatever I like. I can derive it to anything I like. I can mix it with other videos, I can include it in my own, unique production, I can use it for commercial purposes. Most of all, I can use it without fear of retribution. I can use it to make something new, and unique, I can stand on a shoulder of Giants !
Contrast that with something I cannot use, say Britney Spears Music. I can take a video off of youtube and mix it to something new, and re-release it as a new work of my own. You juat cannot do that with closed, copyrighted content.