To use javascript api,
<script type="text/javascript" src="swfobject.js"></script>
<div id="ytapiplayer">
You need Flash player 8+ and JavaScript enabled to view this video.
</div>
<script type="text/javascript">
var params = { allowScriptAccess: "always" };
var atts = { id: "myytplayer" };
swfobject.embedSWF("http://www.youtube.com/v/OyHoZhLdgYw?enablejsapi=1&playerapiid=ytplayer&version=3",
"ytapiplayer", "425", "356", "8", null, null, params, atts);
</script>
To play the youtube with the id:
swfobject.embedSWF
reference: https://developers.google.com/youtube/js_api_referencemagazine