Here is a quick command that you can use to cut a piece of video with FFMPEG.
ffmpeg -sameq -ss [start_seconds] / -t [duration_seconds] -i [input_file] [outputfile]
-ss position
Seek to given time position in seconds. “hh:mm:ss[.xxx]” syntax is also supported.
-t duration
Set the recording time in seconds. “hh:mm:ss[.xxx]” syntax is also supported.
-i filename
input filename
-sameq
Use same video quality as source (implies VBR).
I have more information about video formats and codecs, ripping home video from a DVD, a story board sketching, and more on my Digital Video page.