What to use to quickly cut Audio/Video

• Avidemux (From PPA) - http://avidemux.sourceforge.net/
• OpenShot (From PPA) - https://launchpad.net/openshot/ http://www.openshot.org/ppa/
• Pitivi (From PPA) - http://www.pitivi.org/?go=download

I was going to mention commands like ffmpeg or avconv (The new one) which can OBVIOUSLY split files into groups. For example:

FFMPEG

ffmpeg -ss 00:00:00 -t 00:30:00 -i input.avi -vcodec copy -acodec copy output1.avi
ffmpeg -ss 00:30:00 -t 00:30:00 -i input.avi -vcodec copy -acodec copy output2.avi  
ffmpeg -ss 01:00:00 -t 00:30:00 -i input.avi -vcodec copy -acodec copy output3.avi

Or

ffmpeg -ss 0 -t 100 -i source.m4v -vcodec copy -acodec copy part1.m4v
ffmpeg -ss 100 -t 100 -i source.m4v -vcodec copy -acodec copy part2.m4v  
ffmpeg -ss 200 -t 100 -i source.m4v -vcodec copy -acodec copy part3.m4v  
ffmpeg -ss 300 -t 100 -i source.m4v -vcodec copy -acodec copy part4.m4v

AVCONV

avconv -i input.avi -vcodec copy -acodec copy -ss 00:00:00 -t 00:30:00 output1.avi
avconv -i input.avi -vcodec copy -acodec copy -ss 00:30:00 -t 00:30:00 output2.avi  
avconv -i input.avi -vcodec copy -acodec copy -ss 01:00:00 -t 00:30:00 output3.avi

Or

avconv -ss 0 -i source.m4v -t 100 -vcodec copy -acodec copy part1.m4v
avconv -ss 100 -i source.m4v -t 100 -vcodec copy -acodec copy part2.m4v
avconv -ss 200 -i source.m4v -t 100 -vcodec copy -acodec copy part3.m4v  
avconv -ss 300 -i source.m4v -t 100 -vcodec copy -acodec copy part4.m4v

Or do some script like here: http://icephoenix.us/notes-for-myself/auto-splitting-video-file-in-equal-chunks-with-ffmpeg-and-python/

With new version from ubuntu avconv

avconv -i srcFileName -c:a copy -c:v copy -ss 00:03:40 -t 00:01:12 targetFileName

• First argument time is from time
• Second argument is duration (not end time) duration may be either in seconds or in "hh:mm:ss[.xxx]" form.

To specify end time instead, use the option -to [end time].

Please refer to ffmpeg documentation for more informations

kdenlive is (in my experience) the easiest software which will allow you to perform that task in a few steps and without problems. Even so, the OpenShot Video Editor project is also useful but it yet needs lots of hard work to get closer to the kdenlive.

Here are a screenshot of the kdenlive and openshot respectively:

Good luck!