BitmapData and movieclip registration

private function takeSnapshot(picSubject:MovieClip, offSet:Boolean, parentClip:MovieClip) {
 
		var bmd:BitmapData = new BitmapData(picSubject._width, picSubject._height, true, 0xFF0000);
 
		if (offSet) {
			var mat:Matrix = new Matrix();
			mat.translate(picSubject._width/2, picSubject._height/2);
			bmd.draw(picSubject, mat);
		} else {
			bmd.draw(picSubject);
		}
 
		var mc:MovieClip = parentClip.attachMovie("bmdHolder", "bmdHolder", parentClip.getNextHighestDepth());
 
		mc.bmdHolderShim._width = picSubject._width;
		mc.bmdHolderShim._height = picSubject._height;
 
		mc.attachBitmap(bmd, mc.getNextHighestDepth());
 
		return mc;
 
	}