Trouble downloading "iTunes Extra" content.

I recently bought a movie that gave me the option to download a digital copy. I was able to use the redemption code to download the movie with no problems but the iTunes Extra isn't downloading, it keeps telling me that there is "An Unknown Error (-50)." So I looked that up on the Support page and followed the directions they had but it didn't work. It told me they couldn't find the necessary file [the code was "(-120)"]. So I'm at a loss here, at this point I don't really care whether I get the iTunes Extra or not but it constantly pops up to tell me that it can't download the content everytime I use iTunes and it's getting frustrating. Can anyone help me fix this?