You might want to try the recordmydesktop package. It supposedly grabs video
and audio. It's got a GTK frontend in gtk-recordmydesktop package.
That and other screencasting programs (like SimpleScreenRecorder) grab sound
from the microphone. That's why I would like the output to be treated as an
input as well.
http://outrec.sourceforge.net/
Cool. That's not perfect (it would be better if it became detected as a
microphone, so that other programs that record sound could be used), but it
would work.