Slick slider code testing with slower slides and auto play on videos

HTML

<div class="slider">
  <div>
    <iframe src="https://www.youtube.com/embed/dQw4w9WgXcQ"></iframe>
  </div>
  <div>
    <iframe src="https://www.youtube.com/embed/2Vv-BfVoq4g"></iframe>
  </div>
  <div>
    <iframe src="https://www.youtube.com/embed/NBfi8OEz0rA"></iframe>
  </div>
</div>

CSS

.slider {
  width: 80%;
  margin: 0 auto;
}

.slick-slide {
  margin: 0px 20px;
}

iframe {
  width: 100%;
  height: 400px;
  border: none;
}

Scripts

<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/slick-carousel/1.8.1/slick.min.css"/>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/slick-carousel/1.8.1/slick.min.js"></script>

Javascript

$(document).ready(function(){
  $('.slider').slick({
    infinite: true,
    slidesToShow: 1,
    slidesToScroll: 1,
    autoplay: true,
    autoplaySpeed: 4000, // set the autoplay speed to 4 seconds
    speed: 1000, // set the slider transition speed to 1 second
    responsive: [
      {
        breakpoint: 768,
        settings: {
          arrows: false,
          dots: true
        }
      }
    ]
  });

  // autoplay the YouTube video when it appears
  $('.slider').on('beforeChange', function(event, slick, currentSlide, nextSlide){
    var video = $(slick.$slides[nextSlide]).find('iframe');
    if (video.length) {
      video.attr('src', video.attr('src') + '&autoplay=1');
    }
  });
});