Here's a little nugget from an interview with subversive artist Ron English about the the documentary(?) by Banksy, Exit Through The Gift Shop:

Here's what actually happened: When we first met Thierry, he was supposed to be making a movie about Shepard. He was filming Shepard all the time, wherever he went. They made a deal, 50/50, we'll make a movie. They shot for five years doing this, Shepard in his Spiderman prime, leaping off buildings and stuff. At the end of five years, Shepard says "Alright, let's put the movie together," and Thierry said "I'm not giving you the footage." He's actually quite smart and can be a little devious-he figured "I just took away five years of your fame," because in his heart, Thierry always wanted to be the artist. He figured he was messing up his competition, in a way, and holding onto valuable footage. Shepard didn't quite know what to do and filed a lawsuit against Thierry.

Then Banksy figured "I'm in the same situation, he has tons of footage for me." He had some of the only footage of Banksy where you could actually see who he was. So he calls up Thierry and said "I'm sending you a first-class ticket to London, get on the plane, I have to talk to you." That's when he told Thierry that he would make a movie about him instead, in exchange for the footage, which Thierry turned over to Banksy. That's when they realized that the footage wasn't nearly what they thought it might be, but it turns out they did get a different sort of treasure trove, because you've got a portrait of this weird guy, Thierry.

Banksy is as smart as people think he is, and then some."