OpenShot Video Editor is a free, open-source, non-linear video editor. It can create and edit videos and movies using many popular video, audio, and image formats. Create videos for YouTube, Flickr, Vimeo, Metacafe, iPod, Xbox, and many more common formats!

Features:
* Multiple tracks (layers)
* Compositing, image overlays, and watermarks
* Support for image sequences (rotoscoping) * Key-frame animation
* Video and audio effects (chroma-key) * Transitions (lumas and masks)

Install

Openshot can be available from Ubuntu Software Center. To keep it updated, you can add the PPA:

sudo add-apt-repository ppa:jonoomph/openshot-edge
sudo apt-get update
sudo apt-get install openshot

Launch from Applications -> Sound & Video menu.