Available through TestTube (sort of like Gmail's Labs for YouTube), the Google team announced a new 'edit video in the cloud' feature via the YouTube blog. You can use it to add a soundtrack to your current videos, mash videos together or edit out slow or boring parts at the beginning or end of your videos.
- 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
It's pretty self-explanatory but if you need a demo, check out the moderately annoying video from YouTube's rewboss below.