Currently Being ModeratedApr 20, 2013 3:21 PM (in response to schou479)
I suggest that you use SHARE/MOVIE and choose the size that you want for YouTube. Save it where you can find it.
Then use YouTube in a web browser to upload your movie. In addition to letting you upload longer than 15 minutes, you can cue up multiple movies, and you can continue editing in iMovie while they upload.