whats the best free editing system to use to make a YouTube video??

system? u mean program? window movie maker is good but the best for me is sony vegas pro 9.0

Just as the other person said, あなた can find Windows Moview maker with the Windows XP service(wrong spelling?) pack! So all あなた have to do is go to your C:\ hard drive, Then open the folder called "Program Files", After that you'll find it if your PC atleast has the service pack!
And あなた can download Sony Vegas Pro!
Tip: If あなた make something with Windows Movie Maker, You'll need time to make a flashy awesome cool Video, Other then that everything will be normally awesome but it's really easy to use, But if あなた use Sony Vegas Pro, Your Video WILL be flashy even if you're a bigginer BUT it'll take time to master and NOT easy to make stuff!

one true media