Well worth a watch, though they had to do that scare tactic of opening up a film can full of brown dust or black goo or white mold every two minutes. Chances are those films were boring anyway - most are. Archivists don't always make value judgements like that. I watched a "rediscovered" silent film, The Life Story of David Lloyd George awhile ago - it should have stayed lost.

The more pressing question is what are we doing to preserve our precious film actors? Remember Emily Watson? Cute star of films from the 90s like Breaking the Waves and Trixie? Now rather gaunt and careworn. Why aren't we putting her in a climate-controlled, dark storage facility? Before she crumbles into dust! That would be money well spent.

Films live in our memories. They live in our hearts. But they don't necessarily live for very long in our archives.

We think of cinema as a fixed, unchanging, undying phenomenon. They delighted us, horrified us, titillated or amused us. This spectacular documentary teaches us that those memorable pictures might as well be stored on an Etch-a-Sketch.