This is the component that I use to create the flash transition
http://www.jumpeyecomponents.com/Flash-Components/Skins-and-Patterns/MCTE-V3-Square-Pack-48/
You also can make some change in the ActionScript, like alpha, speed and how many pictures.
Here is my example: http://yl372.aisites.com/mm3301/MM3301_wk3.html
import mx.transitions.Tween;
stop();
btnPlay._alpha = 50;
btnPlay.onRollOver = function()
{
btnPlay.oTween = new Tween(btnPlay, "_alpha",Strong.easeOut, 50, 100, 15, false);
}
btnPlay.onRollOut = function()
{
if(btnPlay._alpha > 50)
{
 btnPlay.oTween = new Tween(btnPlay, "_alpha", Strong.easeOut, 100, 50, 15, false);
}
}
btnPlay.onRelease = function()
{
var counter:Number = 0;
var btnPlayRollOut:Function = btnPlay.onRollOut;
var btnPlayRollOver:Function = btnPlay.onRollOver;
btnPlay.oTween = new Tween(btnPlay, "_alpha",Strong.easeOut, 100, 0, 10, false);
btnPlay.onRollOut = function()
{}
btnPlay.onRollOver = function()
{}
btnPlay.oTween.onMotionFinished = function()
{
 var listener:Object = new Object();
 mcte._targetInstanceName = "mc1";
 mcte.transitionEffect("show"); 
 mcte.addEventListener("onTransitionEnd", listener);
 listener.onTransitionEnd = function()
 {  
  mcte.removeEffect();
  btnPlay.swapDepths(mcBcg);
  btnPlay.oTween = new Tween(btnPlay, "_alpha" ,Strong.easeOut, 0, 50, 30, false);
  mcte.removeEventListener("onTransitionEnd", listener);
 
  btnPlay.oTween.onMotionFinished = function()
  {
   btnPlay.onRollOver = btnPlayRollOver;
   btnPlay.onRollOut = btnPlayRollOut;
  }
 }
}
}