YouTube Player APIを使用してYouTube動画を再生し始めてから指定した秒数経過後にバナーなどの要素を出現させる方法（iframeタグを使用）のデモページ

.wrap {
  width: 768px;
  margin: 50px auto 0;
 }

.text {
  margin: 0 0 20px;
  text-align: center;
}

#movie {
  position: relative;
  width: 100%;
  padding-bottom: 56.25%;
}

#movie iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

.movie_btn {
  display: none;
  width: 350px;
  margin: 50px auto 0;
}

.movie_btn a {
  display: block;
  padding: 30px 0;
  text-align:center;
  font-weight: 700;
  color: #fff;
  background: #c00;
}

@media screen and (max-width:640px){
  .wrap {
    width: 100%;
  }
}
  

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 player;

function onYouTubeIframeAPIReady() {
  player = new YT.Player("player",{
    events: {
      'onStateChange': onPlayerStateChange
    }
  });
}

var check = false;
function onPlayerStateChange(event) {
  setTimeout(ytTime, 100);

  //ここで経過秒数を指定
  var ytSeconds = 10;

  function ytTime() {
  if (!check) {
  console.log(player.getCurrentTime());
    if(ytSeconds < player.getCurrentTime()){
      $('.movie_btn').fadeIn('slow');
      check = true;
    }else{
      setTimeout(ytTime, 100);
    }
  }
 }
}