может такой вариант сгодиться работает с
http://www.youtube.com/watch?v=gAnhjo25udo
http://youtube.com/watch?v=gAnhjo25udo
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"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body>
<script language="JavaScript" type="text/javascript">
for(text="[youtube]http://youtube.com/watch?v=yl6j4xFvVdU[/youtube] [youtube]http://www.youtube.com/watch?v=ERAhCzkq3ds&feature=related[/youtube] [youtube]http://www.youtube.com/watch?v=sSgPDKG6bB0[/youtube]";text.search(/\[youtube\](.*?)\[\/youtube\]/g)>=0;){t=text.split("[youtube]");if(t[1]){t2=t[1].split("[/youtube]");if(t2[0]){var ss2009=t2[0].replace("watch?v=","v/");ss400='src="'+ss2009+'&hl=ru&fs=1"';text=text.replace("[youtube]"+t2[0]+"[/youtube]","<embed "+ss400+" type=application/x-shockwave-flash allowscriptaccess=always allowfullscreen=true width=280 height=245></embed>")}else text=
text.replace("[youtube]"+t2[0]+"[/youtube]","")}}document.write(text);
</script>
</body>
</html>