Part of Video Blogging is creating screen casts which show a user how to do something on the computer itself. There is the wp:Screencast page that goes into more detail on the subject. This page dives into my own personal experieces and recipies for creating screencasts on Kubuntu using Free Open Source Software.
Record My Desktop
The first thing you discover is that the program "Record My Desktop" is the one you'll probably want to use. It comes with a KDE and a GTK front-end. I have only tried the GTK front-end which looks more mature.