// 2. This code loads the IFrame Player API code asynchronously.

      var tag = document.createElement('script');

      tag.src = "https://www.youtube.com/iframe_api";

      var firstScriptTag = document.getElementsByTagName('script')[0];

      firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

var section = {

  start: 30,

  end: 58

};

// 3. This function creates an <iframe> (and YouTube player)

//    after the API code downloads.

var player;

function onYouTubeIframeAPIReady() {

  player = new YT.Player(

    'player',

    {

      height: '0',

      width: '0',

      videoId: 'S5xDk7dnmbw',

      events: {

        'onReady': onPlayerReady,

        'onStateChange': onPlayerStateChange

      }

    }

  );

}

function onPlayerReady(event) {

  player.seekTo(section.start);

  player.playVideo();

}

function onPlayerStateChange(event) {

  if (event.data == YT.PlayerState.PLAYING) {

    var duration = section.end - section.start;

    setTimeout(restartVideoSection, duration * 1000);

  }

}

function restartVideoSection() {

  player.seekTo(section.start);

}