You can easily record desktop tutorials encoded in Ogg/Theora/Vorbis using recordMyDesktop (see my screen recording post for details). However, sometimes your recording ends up with a bit of cruft at the ends that you want to crop out. Enter oggz, a simple tool for minor Ogg stream editing.
For example, you can quickly extract the first 657 seconds of a video with
$ oggz chop -e 657 -o output.ogv input.ogv
$ vorbiscomment -a input.ogv -t "ARTIST=Some Guy" -t "TITLE=A Title"