Problem
How to flip movieClips horizontally
Solution
Use scaleX=-1 and scaleX=1
Detailed explanation
stage.addEventListener(KeyboardEvent.KEY_DOWN, starMoving);
var speed:Number=20;
function starMoving(event:KeyboardEvent):void {
trace(event.keyCode);
switch (event.keyCode) {
case Keyboard.LEFT :
face_mc.x-=speed;
face_mc.scaleX=-1;
if (face_mc.x
}
break;
case Keyboard.RIGHT :
face_mc.x+=speed;
face_mc.scaleX=1;
if
(face_mc.x+face_mc.width>container_mc.x+container_mc.width) {
face_mc.x=container_mc.x+container_mc.width-face_mc.width;
}
break;
default :
break;
}
}

Source:
flip horizontal movie clip
