Responsive BG Video – http://codepen.io/AllThingsSmitty/pen/KNPOjp

res-video.css

:root {
  font-size: calc(1vw + 1vh + .2vmin);
}
body {
  background: #111;
  font: 1rem/1.1 "Montserrat", sans-serif;
  margin: 0;
}
section {
  height: 100%;
  overflow: hidden;
  position: relative;
}
video {
  bottom: 0;
  height: 100%;
  left: 0;
  margin: 0;
  padding: 0;
  top: 0;
  right: 0;
  width: 100%;
}
.vignette {
  background: rgba(0, 0, 0, 0.6);
  height: 100%;
  left: 0;
  position: fixed;
  top: 0;
  width: 100%;
  z-index: 1;
}
h1 {
  color: #fff;
  font-size: 4rem;
  margin: 3rem;
  position: absolute;
  text-transform: uppercase;
  width: 100%;
  z-index: 2;
}

res-video.html

<section>
  <div class="vignette"></div>
  <h1>Advertising.<br>Digital.<br>Social.</h1>
  <!-- video from http://evb.com -->
  <video loop preload autoplay>
    <source id="source_polar_mp4" src="http://d2pxo8g26zv991.cloudfront.net/wp-content/uploads/2014/10/HomeVideo_v04_1.mp4" type="video/mp4;codecs=&quot;avc1.42E01E, mp4a.40.2&quot;">
    <source id="source_polar_webm" src="http://d2pxo8g26zv991.cloudfront.net/wp-content/uploads/2014/10/HomeVideo_v04_1.webm" type="video/webm;codecs=&quot;vp8, vorbis&quot;">
  </video>
</section>