// This is how you pause a YouTube video on slide change.
let $slider = new Swiper($sliderWrapper, {
  on: {
    slideChange: function (el) {
      $('.swiper-slide').each(function () {
        // Find the YouTube iframe.
        var youtubePlayer = $(this).find('iframe').get(0);

        if (youtubePlayer) {
          // Attempt to send a command to the player to stop the playing of the video.
          youtubePlayer.contentWindow.postMessage('{"event":"command","func":"pauseVideo","args":""}', '*');
        }
      });
    }
});