There is a fantastic documentary about a documentary, Santiago, ( http://pt.wikipedia.org/wiki/Santiago_(document%C3%A1rio) http://pt.wikipedia.org/wiki/Santiag

There is a fantastic documentary about a documentary, Santiago, ( http://pt.wikipedia.org/wiki/Santiago_(document%C3%A1rio) http://pt.wikipedia.org/wiki/Santiago_(document%C3%A1rio) , unfortunately in portuguese), that explores this very issue. When he was young, the director tried to shoot a documentary about his family's former butler, but ended up discarding the footage. Years later, after the butler was dead, he came back to the footage and realized what a dick he was during the whole process. He then edited it to tell a story of the common blindness of the documentarist. It's touching, and makes it so you will never watch a documentary in the same way after watching it. I have no idea if it was released internationally, but it's definitely worth seeing.