How can I fix a corrupted iPhone 4 video file?

I have a video that i recorded back in October with my iPhone 4, but for some reason now it won't play. It says "The movie could not be opened. The file is not a movie file. I have tried a bunch of different corrupted video repair software programs....i got one to convert a little bit of it (you have to pay over $100 to get the full converted video.) While the video is a nice short little video, it isn't worth $100 to have it ...however, is there another way to fix these? i know it helps to have a video that is a reference video shot around the same time, which i do. if anyone has any suggestions, i would greatly appreciate it.