YouTube VideoBackground

youtube-video.css

iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;

  @media (min-aspect-ratio: 16/9) {height: 300%; top: -100%}
  @media (max-aspect-ratio: 16/9) {width: 300%; left: -100%}
}

youtube-video.js

// <script src="https://www.youtube.com/iframe_api"></script>
var videoId = 'leSaAaWrkK0',
    muted = 0;

if (videoId) {
  $('[data-youtube]').html('<div id="player"></div>');
  function onYouTubeIframeAPIReady() {
    var player = new YT.Player('player', {
      videoId: videoId,
      events: {'onReady': onPlayerReady},
      playerVars: {controls: 0, showinfo: 0, rel: 0, autoplay: 1, loop: 1, iv_load_policy: 3, mute: muted, playlist: videoId}
    });
  }
  function onPlayerReady(event) {event.target.playVideo()}
}