iMovie is not uploading videos to YouTube When I click File > Share > YouTube (username) a box pops up, but the "next" button is not highlighted and is not clickable. I've also tried to upload the files from the YouYube website but when I do I get this error and a 0% upload: 

"We did not recognize the format of this file, but we will try to process it anyway. See this article on recommended formats for more information."

The file extension is .imovieevent.

What can I do to successfully upload to YouTube?
I don't have much experience with iMovie, but I would suggest exporting your video, then uploading it to YouTube. In the past I have used inbuilt uploading mechanics and they don't tend to be the most reliable of things.