Thanks for letting me know. iMovie was acting a little funny during editing. I restarted iMovie, and it seemed to clear it up a bit, but it looks like it messed up again during conversion.
Hmmm... I just checked the memory, and I only have 4.6GB free. Considering I have 16GB, that isn't good. I probably need to reboot. I will reboot in the morning if it doesn't clean up by then.