I'm having a similar problem to most people who can't get music to iTunes except I can't get movies to iTunes. I tried as many of the music solutions suggested by Lord of the Rings, but none of them work. I have all of the the settings set that he suggested and it still won't work.
The best part is that I downloaded a movie approximately 18 hours ago and it worked fine!
I haven't changed anything since then and the file is the same size and format but it refuses to go to iTunes! Why?