HELP! How to get dynamic variable from URL?

I’m sure by now, you’ve all seen this page:

http://you.youarelame.com/
(replace YOU with any name)

And in this flash movie, in a text area, it shows whatever you type in before the string “.youarelame.com”.

How was this done?

Is it possible to pass a variable to a Flash Movie thru the URL?

Like, for example, if I were to do something like this:
www.mywebsite.com/myflashmovie.swf**?USERNAME=th3Phallex**

could I process the “USERNAME” variable with some code somehow and get it to return my USERNAME back to me in the Flash movie?