loadYoutubeToFillScreen.html

 <div class="video-background">
    <div class="video-foreground">
      <iframe src="https://www.youtube.com/embed/N9Y86YCRRDg?&amp;autoplay=1&amp;loop=1&amp;playlist=N9Y86YCRRDg&amp;rel=0&amp;controls=0&amp;mute=1" frameborder="0" allowfullscreen></iframe>
    </div>
  </div>
  
 <style>
  * { box-sizing: border-box; }
.video-background {
  background: #000;
  position: fixed;
  top: 0; right: 0; bottom: 0; left: 0;
  z-index: -99;
}
.video-foreground,
.video-background iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

@media (min-aspect-ratio: 16/9) {
  .video-foreground { height: 300%; top: -100%; }
}
@media (max-aspect-ratio: 16/9) {
  .video-foreground { width: 300%; left: -100%; }
}
@media all and (max-width: 600px) {
.vid-info { width: 50%; padding: .5rem; }
.vid-info h1 { margin-bottom: .2rem; }
}
@media all and (max-width: 500px) {
.vid-info .acronym { display: none; }
}
</style>