In the age of snide mockumentaries and reality-bending, pseudo-fictive films like "Catfish," it is hard to know what to believe on the silver screen. "Exit Through the Gift Shop," the movie by British street artist Banksy that swept film festivals this year, is no exception. This "documentary" charts artist Thierry Guetta's mounting obsession with street art (and his eventual selling out to a vampiric commercial art world under the name Mr. Brainwash). But is it real, or another Joaquin Phoenix put-on? "The film's power comes from the fact it’s all 100% true," says Banksy.

In a rare email interview with blogger AJ Schnack of All These Wonderful Things, the mysterious street artist asserts that everything we see in theaters actually happened. "Obviously the story is bizarre," he writes. "That's why I made a film about it, but I'm still shocked by the level of skepticism. I guess I have to accept that people think I'm full of shit." Still don't believe him? Consider this argument: "If the movie was a carefully scripted prank you can be sure I would've given myself some better lines," Banksy says.

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Truth can be stranger than fiction, apparently. "This is from the frontline, this is watching an art form self-combust in front of you," Banksy says of the film. "Told by the people involved. In real time. This is a very real film about what it means to 'keep it real.'"

So why did the street artist, famed for his subversive stenciled interventions and satirical installations, decide to do a straight film? "If Michaelangelo [sic] or Leonardo Da [sic] Vinci were alive today they'd be making Avatar, not painting a chapel," he writes. Considering that "Exit Through the Gift Shop" may actually stand as the artist's best work to date, one hopes he'll follow the anachronistic example of his Renaissance forebears and continue making movies.