Exit Through the Gift Shop is Banksy’s 2010 entry into documentary filmmaking, and yet another instance of him painting over someone else’s business because the work just had to be seen.

The feature is made from many hours of golden footage of the meteoric rise of the street art movement that made colour from a “legal grey”. Watch as artists are confronted by police, then see how confused they are when they’re eventually confronted by auctioneers.

Banksy isn’t at the centre of this story, though he certainly might have been at one point. Instead, our protagonist (and lesson in the unlimited power of confidence) is Thierry Guetta, who fails upwards and films in all directions. His obsession of finding Banksy, in capturing the legacy of the artistic underworld, is infectious and the mark of a good documentarian. But there are two caveats:

· He’s not a good documentarian.

· He can’t help himself but be a part of that aforementioned legacy. And he’s not a good street artist either.

At least Banksy doesn’t seem shy to think so. So what Thierry really is is the perfect documentary subject. Thierry and Banksy (and to some extent the rest of the street art world), despite having been friends, exist at odds. Thierry cannot create, and when he comes close, like with the making of the film Life Remote Control, he expects the viewer to pick up the pieces for him.

To Thierry, everything is so exciting that nothing can be cut; and what is derivative to one viewer is a practice of worship to him. Or perhaps you’re someone that believes that Thierry is a good artist. For everyone that does, all the praise that Banksy remembers receiving is valued a little less to him. If street art truly is a movement, then Thierry is a new recruit that’s letting the side down, and this film is a wake-up call.

Formally, the film is made a breeze to digest, never struggling for material or overcomplicating (or underselling) its subject. It is incidentally hilarious, being incredibly short on sane subjects and situations, and knowing precisely how long to dwell before moving on to the next. The edit truly does justice to the scale of street art – it is everywhere, and it is humble, despite constant attempts at appropriation by the elite (this film being one of Banksy’s early instances of fighting back).

Of course, given the context, and given how much the film has to say about art, it’s no wonder that so many people suspect that the central Thierry is an invention; possibly a nightmare Banksy had one too many times now put to film. Banksy is a figure so inscrutable that we cannot tell when he is lying.

But that doesn’t matter. If it’s real, it’s a hyperactive musing on the value of this new art and how it can be done right and wrong. If it’s fake, it’s one of the most meaningfully elaborate pranks ever to adopt the medium.

Tom Farrell