How to do this(example inside) effect?

Any idea, how to do this kind of effect?
http://www.eurorscg4d.ee/Lenny/how_to_do_this.html

Point is, tht the ball is actually invisible, and the mouse drags it. Like the ropes are trying to get away from the mouse.
I think the key is Bezier curve. But I can’t figure it out.

Something relevant like this are these effects:


Any help is appreciated.