Controlling size of movie clip

i am loading an external swf of a video file into an empty movie clip. i want the user to be able to toggle between the initial size of the movie (320x240) and full screen (800x600) by clicking a button. what is the actionscript to control the size of a movie clip? can i do that?

thanks!
-adam

if the external swf begins at a size of 8000x600
force _xscale/_yscale to 50
from 320x240 to 800x600
force _xscale/_yscale to 250

on release event:

on(release){
mc._xscale = 250;
mc._yscale = 250;
trace(mc._width)
trace(mc._height)

}