Seasoned Linux users could easily guess that Gtk-recordmydesktop is a graphical, GTK front-end for the command line tool recordmydesktop. There is also a KDE version, called Krecordmydesktop which uses QT libraries instead of GTK libraries so there is in fact no difference between the two except how the interface looks. I will continue with the GTK version.
GTK-recordmydesktop is present in many mainstream distributions’ repositories. You can install the program using the Synaptic package manager or with sudo apt-get install gtk-recordmydesktop. After the installation, the program will be placed under the “Sound and Video" menu.
When you open up the program, you will be greeted with a small window. Inside this window there is a small demonstration of your desktop, as you see in the screenshot. First, click the “Advanced" button and go through the configuration options. Especially note the “Performance" tab: the more frames per second you set, the larger will be your output file. Under the “Sound" tab, be sure to set your microphone correctly. Under the “Files" tab, do not forget to set the folder where the output file will be saved (otherwise you will have to go through the /temp directory to find it.)
When you are done with the configuration, set the area by clicking and dragging where you want the screen to be recorded. After you finish, you can press the “Record" button in the main window and begin to make your Linux screencasts. Do not forget though, the screencast will be saved as an “ogv" file, which is an Ogg Theora Video file.