TO MAKE A VIDEO MOBILE FRIENDLY ADD THE FOLLOWING CODE

PUT THIS CODE IN THE PAGE'S HEAD

<meta name="viewport" content="width=device-width, initial-scale=1">

<style type="text/css">

img {
max-width: 100%;
height: auto;

}

@media only screen and (max-width: 760px) {

.video-container {
position:relative;
padding-bottom:56.25%;
padding-top:30px;
height:0;
overflow:hidden;

}

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


}

</style>
</head>

PUT THE FOLLOWING CONTAINER AROUND THE YOUTUBE CODE IN THE BODY OF THE DOCUMENT

<div class="video-container"></div>

 

VIEW EXAMPLE

<div class="video-container"><iframe width="853" height="480" src="https://www.youtube.com/embed/k1Pn4jit4DI?rel=0" frameborder="0" allowfullscreen="allowfullscreen"></iframe> </div>