mouse mask in as3

[kagamushu]

Hello,
i am trying to find a way to replicate the following mask in as3:
http://www.webwasp.co.uk/tutorials/a07-mask-on-mouse/images/mx/mouse-mask-mx.php
Basically i need to create a mask that follows the mouse movement.
Another question: How come there are so few tutorials, components for as3 on the web? It's driving me crazy!
thanks...

[neznein9]

background.mask = circle;
circle.startDrag(true);