There is a grainy video of a performance from 1967 that almost all of you will have seen. Initially the camera is shaky but when it steadies someone is walking away from us. The figure seems almost completely unconcerned by its audience, turning its large head only a couple of times to acknowledge our presence before disappearing from sight. The footage finishes before it has even really begun; whilst the initial performance, in all its clarity and certainty, was seen by only a very select group of people, through this blurry memento  it has grown exponentially in reputation. In archives, in films and books, on You Yube even, Bigfoot walks off into the undergrowth again and again and again.

According to what or who you read, or indeed what or who you believe, the legendary Patterson-Gimlin film is one of two things. In the first instance, it might be the thing that Roger Patterson would have us believe it is. The chance recording of a remarkable live encounter; a thin and fleeting window onto an event that was larger and more significant than this meagre documentation could ever do justice to. Alternatively, this much derided bigfoot sighting is actually the fake that so many people believe it to be. In which case, this film becomes something else entirely. Not a document of a performance but the performance itself; a man in a suit and a man with a camera, conducting an unassuming pantomime for the benefit of an audience that has yet to materialise.

The Patterson-Gimlin film appears throughout Ella Good and Nicki Kent’s beguilingly delicate Wild Thing I Love You, present as a thought or a memory even when it isn’t being directly spoken about. Like Roger Patterson and Bob Gimlin, Ella and Nicki are here to convince us of the story of what happened when they went to the woods, and whilst they don’t make the same dramatic claims as their predecessors they come accompanied by a similar collection of fractured recordings to prove to us that they are telling the truth. In a tent for an audience sat on cushions, they describe a journey through northern California; it’s a story made out of tattered fragments of documentation – crackly dictaphone recordings, old VHS videos and the shaky footage from a camera phone sat on the dashboard of a bright red pick-up truck. And once again like Patterson and Gimlin, despite their seeming sincerity and the disarming simplicity of their presentation, we can’t really ever be sure if this is all just make-believe.

Ella and Nicki remind us that the question at the heart of the Patterson-Gimlin footage is not whether we believe in Bigfoot, but how much we can believe in the idea of documentation. Can a recording of the past ever tell us the truth about what happened? Or is it always already beginning to deceive us? After all, since Georges Melies we’ve understood that film has more in common with a magic trick than a photograph; a piece of breathlessly fast slight-of-hand performed by light and machines and the materiality of film itself. As such a film of a theatre show is always a performance of a performance. The camera’s flawed attempt to explain in its own distinctive voice what it was that the show was trying to do.

Thanks in part perhaps to Peggy Phelan’s famous association of performance with disappearance, there continues to be a great deal of ambivalence around the medium’s usefulness as a means of documentation; its inertness overemphasized as a means of foregrounding conventional liveness’ own unique virtues. Rarely if ever have I received a DVD or a video clip to watch without the inevitable disclaimer that such footage is incapable of capturing the live experience. Yet so often this feels like a self fulfilling prophesy, as film’s own potential to perform is almost entirely sacrificed for the sake of allowing the anaemic traces of the live performance to take centre stage. Static and discrete, strangled by the pretence of neutrality and positioned somewhere near the rear of the audience,  film is too often asked to describe in increasingly redundant clarity something that looks approximately like the show it is watching, rather eminently more interesting question of what that show feels like.

In this context the Patterson-Gimlin footage is a valuable reminder that performance is at its best when it is elusive, fleeting and inconclusive and that perhaps consequently the most appropriate way of documenting it is to create a film that is made out as many imperfections and deceptions as the thing it purports to capture; a failure of adequate documentation that paradoxically speaks more confidently and honestly about the work than any number of muted and apologetic recordings of the piece in its entirety. A non-film; a container for the performance that, in Robert Smithson’s words, contains the lack of its own containment. Rather than puzzling over how well we can record a show, we might think about how badly it can be done. Perhaps when the camera talks about theatre its voice should crackle and break, it should stumble over its description and forget as much as it remembers. Patterson and Gimlin, and Ella and Nicki for that matter, seem to understand implicitly that immortality is buried in the imperfections. In the gaps and uncertainties their stories leave, they give us the space to dream of monsters.

Here we are then, back in the Forest again as Bigfoot disappears once more into the undergrowth. We remain uncertain watchers caught between two equally theatrical performances; an ambiguous figure with a loping gait revealing herself in a clearing by a creek, and the revealing of that distant moment to us as we sit here in front of a You Yube clip playing on a laptop or an ipad or an iphone. We feel certain there is some kind of performance going on but we can’t be sure who is performing or even when and whether we were intended to be there or not. As in all the best performances we are lost, time is folding complicatedly in on itself and just possibly there is something moving in the undergrowth.