Код AS3:
import flash.display.Loader;
import flash.net.URLRequest;
import flash.events.Event;
var arr:Array = ["file1.jpg", "ggg.jpg", "smile.png", "123.jpg", "file2.jpg"];
var item:String = arr[Math.floor(Math.random() * arr.length)];
var req:URLRequest = new URLRequest(item);
var loader:Loader = new Loader();
addChild(loader);
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, loaderCompleteHandler);
loader.load(req);
function loaderCompleteHandler(e:Event):void {
loader.removeEventListener(Event.COMPLETE, loaderCompleteHandler);
}