[FMX] maroon5 growing "vines"

I am referring to www.maroon5.com 's revealing/growing yellow/maroon/brown colored vines effect (click one of the menu, say, photos, then wait for the large photo from being textured to clear up), coming out of the photos. I assume this implements a [COLOR=DarkRed]MASKING EFFECT[/COLOR], but, is there a way to do this masking USING ACTIONSCRIPT? I am dumb, sorry, does anyone have any ideas how to do such masking using actionscript?

I appreciate your time thanks…