/* do you ever define what var1 is? Also, you can cut this fist line out completely, because the attachMovie replaces it anyways. depth issues.*/

_root.createEmptyMovieClip("drop"+var1,1);
attachMovie("drop","drop",1); 

//why Stage.height - Stage.height? Isn't that just 0?
drop._x = Math.random()*Stage.width;
drop._y = Stage.height - Stage.height ;

// It's good practice to put all imports at the very top of the page. 
import mx.transitions.Tween;
import mx.transitions.easing.*;

// this isn't fuse is it?
var xPost:Tween = new Tween(drop, "_y", Bounce.easeOut, 0, Stage.height, 5, true);

// This is making it go to the halfway point in the middle of the page?
xPostT.onMotionFinished = function() {
	this.continueTo(Stage.height / 2, 3);
};