Black Box is the corner of Edinburgh International Film Festival devoted to experimental film, including the kind of work that is more often found in the gallery than the cinema.

This year, much of the strand's screen time was given over to Yang Fudong's Seven Intellectuals in Bamboo Forest, an ambitious five-part reworking of third century oral tale The Seven Sages of the Bamboo Grove. Seeing it on the big screen, it is hard to believe that Fudong's epic was first conceived as an installation work. Shot on beautifully grainy 35mm stock in black and white, with note-perfect period costumes on the backs of the players, it is also hard at times to accept that this is a new film - it's as if Fudong has unearthed some lost classics from the 1960s, part of an unknown, impossible Chinese New Wave. The look might be retro, but the cycle's concerns are bang up to date, with the intellectuals making a philosophical and physical journey through contemporary Chinese concerns that results in an ambivalent look at individual freedoms in the context of newly unfettered capitalism. That all might sound terribly heavy-going, but Fudong's lush cinematography and languid pacing make for an immersive viewing experience.

The same cannot be said of the Black Box Shorts programme, which had two loose themes: the use of found footage; and a tendency by film-makers to bash their audiences about the head with relentless repetition.

Johann Lurf's Vertigo Rush takes the form of a single repeated shot, a disorientating zoom into the heart of a wooden copse, which speeds up until the image blurs into abstraction. Over five minutes, it might have been powerful; over 20, it is borderline abusive. Bill Morrison's Who by Water is overlong, too. Like the director's masterwork, Decasia, it collages archive footage, this time focussed on ship passengers preparing to embark. The repeated imagery has a curious poetry to it, but the score undermines the work.

Thank goodness, then, for Belgian artist Nicolas Provost. He uses found footage to mesmerising effect. Plot Point is a concise thriller fashioned from decidedly mundane shots of Manhattan streets. Its swelling orchestral soundtrack and sudden cuts combine to form an essay on the manipulation of cinema audiences that proves its own thesis. Provost's second piece is better still. In Gravity, familiar clinches from Hollywood's golden age are intercut at stroboscopic speed, reducing the history of romantic cinema to a single greeting, embrace and farewell.

Like Provost, Jim Finn is concerned with the mechanics of cinema. His Juche Idea is a mockumentary of sorts, interspersing the travails of an artist-worker housed on an invented North Korean art farm' with examples of her work. These take the form of video art promoting the Juche theories of the title, a state ideology complete with precise instructions from Kim Il-sung on the correct' way in which to make films. Finn pairs quotes from the leader's edicts with scenes from real melodramas, showing that their plots match the theory, practically word for word.

The result is a scathing, hilarious film: a Spinal Tap for North Korea's brutally oppressive regime, if you can imagine such a thing.