The new tools will allow users to edit their clips without needing third-party software or ever having to leave the site.
YouTube says the new tools will allow for cutting of frames, changes the in the soundtrack music, stabilization or rotation of the video, modification of contrast and colors and the ability to add new effects.
When edited, the video remains at the same URL with the same ID, so you don't lose any views/favorites, etc.
From Google:
Written by: Andre Yoskowitz @ 15 Sep 2011 21:45