I use Sony Vegas Pro 8 to edit videos before I upload them to you tube. It allows you to render the videos in a format that results in 2 versions being created , one standard quality and one higher quality. I use it because I have some fast action scenes filming dog sports and the normal youtube quality sucks when there is lots of motion.

Check out www.**youtube.com**/watch?v=2e5FZp1b69k remove the ** and click 'watch in high quality' under where it says views and you'll see a significant difference

Sony Vegas is easy to learn and gives some great results.