Invalid Public Movie Atom - Help Me With My Screwed Up Video?

I created a 3 minute long, 1.07 GB HD Video on Final Cut Express. The file on Final Cut was 20 GB, so once the video was exported to mp4 I deleted the footage. I then made a 28 MB version because I like to keep a lo-res copy on file, and then I opened the 1.07 GB copy in iTunes because I like to have files easily exported to my iPod and such. It opened in iTunes quite easily, so I started to change the tags from Movie to TV Show and pressed “Okay”.

iTunes force quit and restarted. The file was missing from the iTunes screen, so I found it in the Music Folder and tried to reopen it in Quicktime. I got the error message “This movie could not be opened; An invalid public movie atom was found in the movie.”

Okay. Salty.

It will open in VLC, but won’t play until 2 mins in. It will not open Final Cut, Quicktime, or MPEG Streamclip. I assume it is simply a problem in the ID3 tags (because iTunes is a jerk), but googling it turned up a Codecs problem. Either way, all of my video editing and conversion skills mean nothing, because this is a computer code problem, and I am completely at a loss.

SO; Does anyone know how to fix the tags and/or codecs so the freaking video will play? I really don’t want to be stuck with a 28 MB version after all my hard work.

I know a few of my steps seem silly and unreasonable, but telling me so won’t help me now :)

Computer genius help please!!