How to Cut/Split Video using Avidemux

Avidemux is a graphical tool to edit videos. It can open AVI, openDML, MPEG, Nuppelvideo, and BMPs. Most common codecs are supported (M-JPEG, MPEG, DivX, Xvid, huffyuv, WMA, etc.) thanks to libavcodec and libmpeg2. Video can be edited, cut, appended, filtered (resize/crop/denoise), and re-encoded to either AVI (MPEG4/MJPEG) or MPEG 1/2. The Spidermonkey Javascript engine is used to give powerful scripting capabilities.

Installation: 
OpenSuse user can use "1-click" installer to install Avidemux
OpenSuse 11.1 - here
OpenSuse 11.0 - here
After sucessfull installation, open the application (Start >> Application >> Multimedia)

For Ubuntu user, Avidemux can install easily by opening the console and typing

sudo apt-get install avidemux

Once installed, you will find on the menu Applications / Sound & Video / Avidemux

To split a file or a section of a file do the following.
Open and select the file you want to split (File / Open).

Then, with the bar below, select the point where we want to start our video and clicking on the letter A using icon  and mark point B  where you want to end (cut) your video (as shown in the figure below)

Finally from the menu select File / Save / Save Video