"You can capture video of all of the amazing things
happening on your desktop with one of Linux’s many
screencasting applications. These programs are perfect for creating
demonstrations for blogs and tutorials, and for illustrating
projects with more than just still images.
"Many different programs are available, and they all provide a
different set of features, options, and output formats. When
choosing, consider the degree of control you want to have over your
video resolution and whether the video is intended to work on
non-Linux operating systems. Common open source output formats,
such as FLAC and Ogg Theora, work natively on Linux but require
software and plugins on proprietary operating systems. User
interfaces also vary greatly; some applications are nothing more
than an icon in the system tray while others depend on large
interfaces with many options."