Le code :

Security.allowDomain("www.youtube.com");
var player:Object;
var loader:Loader;
loader = new Loader();
loader.contentLoaderInfo.addEventListener(Event.INIT, onLoaderInit);
loader.load(new URLRequest("http://www.youtube.com/apiplayer?version=3"));
function onLoaderInit(event:Event):void
{
addChild(loader);
loader.content.addEventListener("onReady", onPlayerReady);
loader.content.addEventListener("onError", onPlayerError);
loader.content.addEventListener("onStateChange", onPlayerStateChange);
loader.content.addEventListener("onPlaybackQualityChange",onVideoPlaybackQualityChange);
}
function onPlayerReady(event:Event):void
{
trace("player ready:", Object(event).data);
player = loader.content;
player.setSize(550,400);
player.loadVideoById("_XvKvIEik8c", 1);
}
function onPlayerError(event:Event):void
{
trace("player error:", Object(event).data);
}
function onPlayerStateChange(event:Event):void
{
trace("player state:", Object(event).data);
}
function onVideoPlaybackQualityChange(event:Event):void
{
trace("video quality:", Object(event).data);
}

Le lien pour tester en ligne