Edit in JSFiddle

<p style="font-size: 2em; text-align: center">Сжимай экран</p>

<div class="youtube">
  <iframe class="youtube__iframe" src="https://www.youtube.com/embed/zuuObGsB0No">
</iframe>

</div>
.youtube {
  position: relative;
}

.youtube:before {
  content: "";
  display: block;
  padding-top: 50%;
}

.youtube:after {
  content: "";
  position: absolute;
  z-index: 10;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: url(https://i.ibb.co/3zSs9VL/5cb0633d80f2cf201a4c3253-1.png) no-repeat center center;
  background-size: cover;
  pointer-events: none;
}

.youtube__iframe {
  position: absolute;
  top: 2.8%;
  left: 2.8%;
  width: 94.4%;
  height: 94.4%;
  z-index: 2;
  border-radius: 12%;
}

body {
  margin: 0;
}

iframe {
  border: 0;
}