Overlaying a DIV On Top Of HTML 5 Video

Here is a stripped down example, using as little HTML markup as possible.

The Basics

• The overlay is provided by the :before pseudo element on the .content container.

• No z-index is required, :before is naturally layered over the video element.

• The .content container is position: relative so that the position: absolute overlay is positioned in relation to it.

• The overlay is stretched to cover the entire .content div width with left / right / bottom and left set to 0.

• The width of the video is controlled by the width of its container with width: 100%

The Demo

.content {
  position: relative;
  width: 500px;
  margin: 0 auto;
  padding: 20px;
}
.content video {
  width: 100%;
  display: block;
}
.content:before {
  content: '';
  position: absolute;
  background: rgba(0, 0, 0, 0.5);
  border-radius: 5px;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
}

<div class="content">
  <video id="player" src="https://upload.wikimedia.org/wikipedia/commons/transcoded/1/18/Big_Buck_Bunny_Trailer_1080p.ogv/Big_Buck_Bunny_Trailer_1080p.ogv.360p.vp9.webm" autoplay loop muted></video>
</div>