var player;

function onYouTubeIframeAPIReady()
    {
    player = new YT.Player('youtube',
        {
        height: '390',
        width: '640',
        videoId: 'M7lc1UVf-VE',
        playerVars:
            {
            autoplay: 0, // start automatically
            controls: 0, // don't show the controls (we can't click them anyways)
            modestbranding: 1, // show smaller logo
            loop: 1 // loop when complete
            },
        events:
            {
            'onReady': onPlayerReady,
            'onStateChange': onPlayerStateChange
            }
        });
    }

<select id="autoPlayOptions">
  <option value="1">autoplay</option>
  <option value="0">manually</option>
</select>
<script>
var player;
  var autoPlayAction = $("#autoPlayOptions").val();
  player = new YT.Player('player', {
    videoId: 'M7lc1UVf-VE',
    playerVars: { 'autoplay': autoPlayAction, 'controls': 0 },
    events: {
      'onReady': onPlayerReady,
      'onStateChange': onPlayerStateChange,
    }
  });
</script>