Just include this code on a page with videos and see them "magically" become responsive.

responsive-video

var $allVideos = $("iframe[src^='http://player.vimeo.com'],iframe[src^='http://www.youtube.com']");
var $fluidEl = $("figure");
 
$allVideos.each(function() {
      $(this)
        // jQuery .data does not work on object/embed elements
        .attr('data-aspectRatio', this.height / this.width)
        .removeAttr('height')
        .removeAttr('width');
    });
    $(window).resize(function() {
     
    var newWidth = $fluidEl.width();
    $allVideos.each(function() {
          var $el = $(this);
          $el.width(newWidth)
          .height(newWidth * $el.attr('data-aspectRatio'));
        });
}).resize();