I own a Nikon D90 SLR and have recently been having problems viewing my camera's videos in quicktime. Nothing has changed in my camera's movie settings and the file is a supported .AVI file.
When I record my video, everything plays back fine in camera, but when I drag the file into Quicktime, I am given a notification that says, "The document could not be opened. The movie is not in a format that Quicktime Player understands. You may need to install additional software to open this type of file." I have called Nikon support twice and I was given the advice to re-format all of my memory cards, to download the latest version of quicktime (which I already have) and to download Nikon View nx2. But to no avail, Quicktime still will not read my files. This is particularly a problem because I am a photography student and I need to shoot video for a multimedia class. My files have played fine on my computer in the past, and the files will not read on a separate computer, either.