I am trying to run a SplideJS slider. However, when I am trying to insert this code nothing happens afterwards. Do you have any idea how to make it work?

<script src="https://cdn.jsdelivr.net/npm/@splidejs/splide@3.1.7/dist/js/splide.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/@splidejs/splide-extension-video@0.5.3/dist/js/splide-extension-video.min.js"></script>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@splidejs/splide@3.1.7/dist/css/splide.min.css">
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@splidejs/splide-extension-video@0.5.3/dist/css/splide-extension-video.min.css">
<div class="splide">
  <div class="splide__track">
    <ul class="splide__list">
      <li class="splide__slide" data-splide-youtube="some link">
        <img src="some image.jpg">
      </li>
      <li class="splide__slide" data-splide-vimeo="some link">
        <img src="some image.jpg">
      </li>
    </ul>
  </div>
</div>
<script>
document.addEventListener( 'load', function () {
    var splide = new Splide( '.splide', {
        video: {
            autoplay: true,
            mute    : true,
        },
    });
    splide.mount({ Video });
}); 
</script> 

Many thanks in advance!