Link straight from youtube

<iframe src="https://www.youtube.com/embed/n6p6yGpvc7M" width="560" height="315" frameborder="0" allowfullscreen="allowfullscreen"></iframe>

&nbsp;

test 2
<style>
.embed-container {
   position: relative;
   padding-bottom: 39.25%;
   height: 0;
   overflow: visible;
   max-width: 100%;
   width: 70%;
   margin: 0 auto;
}
.embed-container iframe,
.embed-container object,
.embed-container embed {
   position: absolute;
   top: 0;
   left: 0;
   width: 100%;
   height: 100%;
}
</style>

<div class='embed-container'>
<iframe src='https://www.youtube.com/embed/n6p6yGpvc7M' frameborder='0' allowfullscreen></iframe>
</div>