Flex video

Here is a demo showing the usage of responsive-embed class from Zurb Foundation. It keeps the proportion of the embed video player, resulting in a much better looking in various screen sizes. Additional widescreen class or panorama class allows different ratio.

<div class="responsive-embed">
  <iframe width="420" height="315" src="https://www.youtube.com/embed/mM5_T-F1Yn4" frameborder="0" allowfullscreen></iframe>
</div>