Youtube Chromeless Player - Videos With An Id That Contains An Underscore Or Dash Don't Play Although They Play In The Normal Player

I am using the youtube chromeless player and embeding videos with loadVideoById() method problem is that videos with an id that contains an underscore or dash dont play although they play in the normal player. I also tried replacing with a hex value in querystring i.e (%5f) but that did not work I also tried loadVideoByUrl() method with several urls but still they don't load. here is my code

function switchToPlayer(ytid){
var params = { allowScriptAccess: "always"};
var atts = { id: ytid,onmouseover: "this.playVideo()",onmouseout: "this.pauseVideo()"};
swfobject.embedSWF("http://www.youtube.com/apiplayer?border=0&enablejsapi=1&playerapiid="+ytid, 'cell'+ytid, "150", "120", "8", "scripts/expressInstall.swf",null,params,atts);
}
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