The following will allow you to create an full width HTML container that loops an MP4 video such as the one below, within the background.

Step 1

Create the containing div for the video and add content overlay.

 <!-- The video -->
<video autoplay muted loop id="myVideo">
  <source src="https://www.w3schools.com/howto/rain.mp4" type="video/mp4">
</video>

<!-- Optional: some overlay text to describe the video -->
<div class="content">
  <h1>Heading</h1>
  <p>Lorem ipsum...</p>
  <!-- Use a button to pause/play the video with JavaScript -->
  <button id="myBtn" onclick="myFunction()">Pause</button>
</div> 

Step 2

To to get the video and content to render properly paste the following CSS styles in your stylesheet.

 /* Style the video: 100% width and height to cover the entire window */
#myVideo {
  position: fixed;
  right: 0;
  bottom: 0;
  min-width: 100%;
  min-height: 100%;
}

/* Add some content at the bottom of the video/page */
.content {
  position: fixed;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  color: #f1f1f1;
  width: 100%;
  padding: 20px;
}

/* Style the button used to pause/play the video */
#myBtn {
  width: 200px;
  font-size: 18px;
  padding: 10px;
  border: none;
  background: #000;
  color: #fff;
  cursor: pointer;
}

#myBtn:hover {
  background: #ddd;
  color: black;
} 

Step 3 (Optional)

To add some optional video controls to your video load the following JavaScript in the footer of your page.

<script>
// Get the video
var video = document.getElementById("myVideo");

// Get the button
var btn = document.getElementById("myBtn");

// Pause and play the video, and change the button text
function myFunction() {
  if (video.paused) {
    video.play();
    btn.innerHTML = "Pause";
  } else {
    video.pause();
    btn.innerHTML = "Play";
  }
}
</script>

Source: www.w3schools.com