This video offers a quick tutorial on how to use the YouTube VIdeo Editor: http://www.youtube.com/editor

Video editing usually requires installing software packages and having a fair amount of technical savvy. But we think video editing should be fun and easy, so we're introducing a new tool that anyone could figure out: it's an online video editor, now available in TestTube, our ideas incubator.

Without installing any software, it allows you to:

- Combine multiple videos you've uploaded to create a new longer video
- Trim the beginning and/or ending of your videos
- Add soundtracks from our AudioSwap library of tens of thousands of songs
- Create new videos without worrying about file formats and publish them to YouTube with one click -- no upload necessary

Read more here: http://youtube-global.blogspot.com/2010/06/edit-video-in-cloud-with-youtube-video.html