On the surface, this film is a truly enjoyable walk through the history of "outlaw art" from its humble beginnings as street graffiti, through gushing acceptance by the "art world" and to subsequent commercialization / corruption with the arrival of big money speculators and wannabe cool celebs.
However, an interesting and almost casual feature of this film is how Banksy -- who has clearly collaborated with the film-makers -- deliberately allows those who care to triangulate his true identity. By naming names and including detailed interviews with many of his early collaborators, the film casually unmasks our anonymous hero to anyone who know or cares about him or this corner of the art world.
Certainly that would include the many art auction houses who deal in his work and elitist art collectors who pay millions of dollars to hang a piece of public street art in their private mansions.
So, even as the film concludes that Banksy's anonymity is part of his legend, and an important piece of folklore that drives up prices for his art in the private market -- the exact opposite of what a street artist like Banksy desires -- by revealing his identity to anyone who cares, Banksy is pulling off the ultimate prank on the art world speculators and collectors, who now have to shut up about this identity, or risk losing value in their precious collections.
So, brilliantly, Banksy uses the art world's unbridled hubris as the means to reserving his anonymity and legend for the masses, for whom he truly produces his art anyway.
Amazing! Brilliant! And just Banksy (as usual).