its just a transparent image moving over the buttons.They probably assign a variable a value of true whenever a button has been pressed and then false after the movie has loaded. The rollOver only works when not true. Have a look at this http://www.gifsrus.com/testfile/smoothmovementbuttonsmenu.fla
whenever a buton is pressed, pressed = true when the mc stops playing, pressed = false.The rollover only works when pressed !=true
