1   <iframe id="video1" width="450" height="280" src="http://www.youtube.com/embed/TJ2X4dFhAC0?enablejsapi" frameborder="0" allowtransparency="true" allowfullscreen></iframe>
2    <a href="#" id="playvideo">Play button</a>
3    <script>
4     $("#playvideo").click(function(){
5      $("#video1")[0].src += "?autoplay=1";
6     });
7    </script>