Easing + Mouse Over + MC

Dear all, I’m here again seeking help. I’m learning a followease tutorial and get it working but am trying to learn more from this. With this tutorial when mouseover, the arrow marker eases following the mouse. For e.g I have a column of buttons. When the mouse moverover Button1 it plays MC1 and stopped. When it mouseover Button2 it plays MC2 and stopped. How can it be done?