CSS Fluid Width Video

Example :

<div class="video-content">

    <!-- YouTube video code-->

    <iframe width="560" height="349" src="http://www.youtube.com/embed/THEVIDEOID" frameborder="0" allowfullscreen></iframe>

</div>

.video-content {

  position: relative;

  padding-bottom: 56.25%; /* 16:9 */

  padding-top: 25px;

  height: 0;

  iframe {

    position: absolute;

    height: 100%;

    top: 0;

    left: 0;

    width: 100% !important;

    height: 100% !important;

  }

}