Taking a snapshot from a movie clip and storing it

Hi guys !

I need to take a snapshot of a movie clip (only a rectangular of a movie clip, not the whole) and to store it in a variable so I can later show it to the user.

Can you help me ?

use the BitmapData Class:
http://livedocs.macromedia.com/flash/8/main/00001942.html

Defective I have no clue on how to use this class! I read, read, read but didn’t find a way…