I've tried a couple of solutions to make some acceptable screencasts with my linux box.
The first enthusiasm has been spent around the cool vnc2swf application. It creates a cool and simple HTML interface to Flash movie getting the output of your favorite VNC server. My problem is that I don't have a favorite VNC server and I've lost a lot of time trying to deal with VNC configuration without reaching the type of output I was looking for.
Then I've changed direction and looked inside apt-cache: istanbul - Desktop session recorder producing Ogg Theora video Istanbul has a decent user interface that let you choose the window of the area of your screen to be recorded.
Supports only OGG output format.
Then FFMPEG comes out to help: ffmpeg -y -i my_file.ogg -f swf my_swf.swf
last thing to do is an HTML page to add some controls for the movie playing.
I've copied the code from a vnc2swf session and just changed the SWF name inside the Object/Embed HTML object. it works fine to me.