title: Popup video keeps playing in background after closing the popup
body: <p>I have a button that when clicked, pops up a video that can played.
  The problem is that if you close the popup while the video is playing, closing the popup does not stop the video, but it keeps playing in background. </p>
  
  <pre><code>&lt;div&gt;
      &lt;a id="click-me"&gt;Click Me&lt;/a&gt;
  &lt;/div&gt;
  
  &lt;div id="popup-mpdal" style="display:none;"&gt;
      &lt;div class=""&gt;
          &lt;video id="videoplayer" controls poster='&lt;?php echo $block-&gt;getUrl("pub/media/video/")?&gt;whats-your-story.png'&gt;
              &lt;source src='&lt;?php echo $block-&gt;getUrl("pub/media/video/")?&gt;this-is-chris-saint-long-version.mp4' type="video/mp4"&gt;
          &lt;/video&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  
  &lt;script&gt;
      require(
          [
              'jquery',
              'Magento_Ui/js/modal/modal'
          ],
          function(
              $,
              modal
          ) {
              var options = {
                  type: 'popup',
                  responsive: true,
                  innerScroll: true,
                  buttons: [{
                      text: $.mage.__('Continue'),
                      class: '',
                      click: function () {
                          this.closeModal();
                      }
                  }]
              };
  
              var popup = modal(options, $('#popup-mpdal'));
              $("#click-me").on('click',function(){ 
                  $("#popup-mpdal").modal("openModal");
              });
  
          }
      );
  &lt;/script&gt;
  </code></pre>