JSFiddle - React, Tailwind, and code Playground

HTML

<div class="video-crop50">
  <video src="https://www.w3schools.com/howto/rain.mp4" autoplay muted loop></video>
</div>

<p>Lorem ipsum</p>

CSS

body {
  margin: 0;
}

.video-crop50 {
  position: fixed;
  top: 0;
  left: 0;
  overflow: hidden;
  width: 50%;
  height: 100vh;
  z-index: -1;
}

.video-crop50 video {
  min-width: 100vw;
  min-height: 100vh;
}