Embed video sin franjas negras al 100% y height auto

.embed-container {
  position: relative;
  padding-bottom: 56.25%;
  overflow: hidden;
}

.embed-container iframe,
.embed-container object,
.embed-container embed {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
}

<div class='embed-container'>
<iframe src="https://player.vimeo.com/video/210572562?title=0&byline=0&portrait=0" frameborder="0" webkitallowfullscreen mozallowfullscreen allowfullscreen></iframe>
</div>