[X2Go-User] x2godesktopsharing, what's the point?

Can someone explain me when I could use x2godesktopsharing?

From the doc it looks like you needed it to share a desktop but I managed to share desktops without installing it (I only in installed x2goserver).

I made a small video to explain better the situation: http://bit.ly/TdpcxE

I'm on Ubuntu 12.10.

Second questions. With x2godesktopsharing installed I have an applet (http://bit.ly/TZosgs) in the systray where I can activate/deactivate desktop sharing but it has no effect (I can connect with a client when Deactivate desktop sharing is selected) and I don't understand how to add users (Granted user... and Banned users... are always greyed out...)

Thanks Marco