テスト２

!-- CSS読み込み -->

link rel="stylesheet" href="./css/magnific-popup.css">

!-- 動画のリンク、サムネイル呼び出し -->

p class="md_iframe_image">

   <a href="//www.youtube.com/watch?v=YouTube動画のID" class="md_popup-iframe">
       <img src="//i.ytimg.com/vi/YouTube動画のID/mqdefault.jpg" alt="">
   </a>

/p>

<!-- jQueryの読み込み -->

script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>

script src="//cdnjs.cloudflare.com/ajax/libs/magnific-popup.js/1.1.0/jquery.magnific-popup.min.js" async=""></script>

script>

   $(window).on('load', function(){
       $('.md_popup-iframe').magnificPopup({
           type: 'iframe',
           mainClass: 'mfp-fade',
           removalDelay: 200,
           preloader: false
       });
   });

/script>