basic use case:
1) open a contact's message windows from pidgin. (some one who ask you howto use a tool per example).
2) press a button and the curso turns in a cross indicating that you can track a rectangle, track the rectangle.
3)the pidgin offers to your friend to receive the video stream of your desktop area. your friend accept.
4)Now your friend can see like in a webcam windows frame what you are doing inside that rectangle.

easy and fast, without worry about IP, ssh tunneling, permissions, since you can select just the needed area the transmission will occur faster and clear than in VNC, you won't need explain what VNC is, you won't need know what VNC is. Only a simple and useful feature that the people realize by their-selfs how to use it.