i use final cut pro x or i can use imovie.. but i found out what was wrong, i have to put h.264 options. i had just stuck with the same as my camera settings which were huge..Full 1080p video, around 20mins long, is about 2.6GB for me. I let FCPX do all the work, just select the option to share to YouTube once I'm finished with my project and let it get on with the rest!
Note to OP - what software are you currently using for creating/rendering your videos? Its probably just your render settings that need tweaking......