Install the following script above </body> usually at the bottom
<script>//<![CDATA[/*! llyv.js v0.1.0 */!function(){"use strict";for(var t=document.querySelectorAll(".llyv"),e=0;e<t.length;e++){var i=document.createElement("div");i.className="llyv-play-btn",t[e].appendChild(i);var l=document.createElement("img");l.src="https://img.youtube.com/vi/"+t[e].dataset.id+"/hqdefault.jpg",t[e].appendChild(l),t[e].addEventListener("click",function(){var t=document.createElement("iframe");for(t.setAttribute("src","https://www.youtube.com/embed/"+this.dataset.id+"?rel=0&showinfo=0&autoplay=1"),t.setAttribute("frameborder","0"),t.setAttribute("allowfullscreen","");this.firstChild;)this.removeChild(this.firstChild);this.appendChild(t)})}}();//]]></script>
Next, install the CSS lazyload above </b:skin>
/*! llyv.css v0.1.0 */ .llyv,.llyv .llyv-play-btn,.llyv img{cursor:pointer} .llyv{background-color:#000;margin-bottom:20px;position:relative;padding-top:56.25%;overflow:hidden} .llyv img{width:100%;top:-16.82%} .llyv .llyv-play-btn{width:100px;height:60px;background-color:#282828;z-index:1;border-radius:9px} .llyv .llyv-play-btn:before{content:"";border-style:solid;border-width:15px 0 13px 28px;border-color:transparent transparent transparent #fff} .llyv .llyv-play-btn:hover{background-color:red} .llyv .llyv-play-btn,.llyv .llyv-play-btn:before,.llyv iframe,.llyv img{position:absolute} .llyv iframe{height:100%;width:100%;top:0;left:0}.llyv .llyv-play-btn,.llyv .llyv-play-btn:before{top:50%;left:50%;transform:translate3d(-50%,-50%,0)}
Use the following markup to install YouTube Lazyload in an article or post.
<div class="llyv" data-id="id-video"></div>