responsive_iframe_video_embedding.html

<div class="myvideo">
	<iframe src="http://www.youtube.com/embed/MY-VIDEO" frameborder="0" allowfullscreen></iframe>
</div>

responsive_iframe_video_embedding.scss

.myvideo{
    position: relative;
    padding-bottom: 56.25%;
	padding-top: 30px;
	height: 0;
	overflow: hidden;
	iframe,  	
	object,  
	embed {
		position: absolute;
		top: 0;
		left: 0;
		width: 100%;
		height: 100%;
	}
}