Useful commands for ffmpeg.

Cut a video.

ffmpeg -sameq -ss [start_seconds] -t [duration_seconds] -i [input_file] [outputfile]

Convert to ogv for the web.

ffmpeg -vcodec libtheora -g 15 -qscale 6 -acodec libvorbis -ac 2 -aq 3 -i [input_file] [outputfile]