var l:Loader = new Loader();
l.contentLoaderInfo.addEventListener(ProgressEvent.PROGRESS, loop);
l.contentLoaderInfo.addEventListener(Event.COMPLETE, done);
l.load(new URLRequest("main.swf"));

function loop(evt:ProgressEvent):void {
	var perc:Number = evt.bytesLoaded / evt.bytesTotal;
	percTxt.text = Math.ceil(perc*100).toString();
}

function done(evt:Event):void {
	removeChildAt(0);
	percTxt = null;
	addChild(l);
}