Cinelerra is the most advanced non-linear video editor and compositor for Linux. Cinelerra also includes a video compositing engine, allowing the user to perform common compositing operations such as keying and mattes.Cinelerra
To download click here
Also you can try OpenShot.
OpenShot has many great features, such as trimming and arranging videos, adjusting audio levels, transitions between videos, compositing multiple layers of video, chroma-key / green screen effect, and support of most formats and codecs.
What really sets OpenShot apart from other video editors is the easy-to-use user interface.OpenShot
To install OpenShot, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:
sudo add-apt-repository ppa:openshot.developers/ppa
sudo apt-get update
sudo apt-get install openshot openshot-doc