This is a remarkable documentary, informative, interesting and successful in clarifying what is, for many, something of a mysterious process. The contributions to film making of directors, actors, designers, cinematographers and sound recordists is self evident, but the film editor's role has seldom been understood nor its importance fully recognised. This documentary is the first to give directors and editors an opportunity to explain exactly what goes on in the editing room and they have done it superbly. What a pity then, that references to the history of film editing woven into this story are cursory, inadequate and in some instances completely wrong. Martin Scorsese refers to Edwin Porters' 1902 film, Life of an American Fireman, as the very first film to be edited using crosscutting as a structuring device, and the commentary supports this view, despite convincing evidence to the contrary that was discovered in 1978. In fact the earliest discovered examples of this practise date from 1906. Equally mistaken is the assertion, made several times in this prize-winning documentary, that D.W.Griffith originated the important editing practise of action matching. In fact there is clear evidence of action matching in a British film made as early as 1903 and Griffith's first film was not made until 1908. There is considerable evidence that Griffith considered action matching to be of very little importance, and when used in his films it is often ill judged and clumsy. All this is curious in a documentary that seeks to explain the history and practise of film editing. One might have expected research on the topic to be as well informed as the comments made by most of the contributors, particularly given that the scriptwriter is Professor Mark Jonathan Harris of the School of Cinema and Television, University of Southern California.