A documentary, The Cutting Edge , illustrates the entire history and technique of film editing from the very earliest days to up 2004. Interviews with Steven Spielberg, Michael Kahn, James Cameron, George Lucas, Alexander Payne, Walter Murch, Anthony Minghella, and others bring needed insight into how the film editor fits into the creative process.
The Big Sleep comes with both the theatrical version and a recently discovered pre-release cut. The differences a little editing can make are fascinating.
John Dahl's Joy Ride comes with four alternate endings.
The 2-disc set of Hannibal has a multi-angle edit gallery for the beginning filmmaker to study what goes into making multi-angle action scene.
The English Patient (Miramax Collector's Edition) includes a master class on editing with Anthony Minghella. Excellent explaination of why deleted scenes got cut out. For some reason Walter Murch, the brilliant editor of The English Patient is not included in the feature.
Die Hard (two disc edition) has a great supplemental feature on editing 2 scenes from the raw footage to the finished film. Also a great three minute clip on "to letterbox or not to letterbox" which shows why it makes a difference.
Star Wars Episode I: The Phantom Menace features a documentary where Wallter Murch, Francis Ford Coppola, and Phillip Kaufman explain why scenes get deleted. There is a priceless story of Walter Murch removing a moment from the film "Julia" and the director saying that the scene being cut from was the scene that got him started on the project to begin with. Not a great movie but excellent special features.