Very simple method to add custom poster frame to youtube video without using youtube API. This code is also valid in browsers not supporting window.postMessage (API uses postMessage). The trick is adding the iframe in a comment. Javascript reads comment contents and saves iframe definition to a var. When JQuery (for the sake of brevity, not real…

youtube-poster-frame.css

.video { position: relative; padding-bottom: 56.25%; /* 16:9 */ height: 0; }
.video img { position: absolute; display: block; top: 0; left: 0; width: 100%; height: 100%; z-index: 20; cursor: pointer; }
.video:after { content: ""; position: absolute; display: block; 
    background: url(play-button.png) no-repeat 0 0; 
    top: 45%; left: 45%; width: 46px; height: 36px; z-index: 30; cursor: pointer; } 
.video iframe { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }

/* image poster clicked, player class added using js */
.video.player img { display: none; }
.video.player:after { display: none; }

youtube-poster-frame.html

<div class="video">
    <img src="poster.jpg">
    <!-- <iframe width="940" height="529" src="http://www.youtube.com/embed/rRoy6I4gKWU?autoplay=1" frameborder="0" allowfullscreen></iframe>-->
</div>

youtube-poster-frame.js

$(function() { 
    var videos  = $(".video");

        videos.on("click", function(){
            var elm = $(this),
                conts   = elm.contents(),
                le      = conts.length,
                ifr     = null;

            for(var i = 0; i<le; i++){
              if(conts[i].nodeType == 8) ifr = conts[i].textContent;
            }

            elm.addClass("player").html(ifr);
            elm.off("click");
        });
});

I´ve not tested it, but i think that ?autoplay=1 won´t work on IOS & Android, so users will have to make a second click... Any solution to this?

I've tried it, but the only thing that works is setting the iframe, but without the id, so it doesn't work. And it woun't remove the iframe with a second click, it just sets another iframe..

Really good job on the site, Keep up the good work!
Baa baa Black Sheep

can you explain what this for statement does?

for (var i = 0; i < length; i++) { if (conts[i].nodeType == 8) ifr = conts[i].textContent; }

@thecopelandcollective

That code is iterating through the contents of the element, and if it's an HTML comment (https://developer.mozilla.org/en-US/docs/Web/API/Node/nodeType .... see constant value of 8) then essentially uncomment it, which in turn loads the iframe.

its not working the iframe not loads

hi sorry to disturb you guys, but where do I put the script? just before the div from the video ?

Works perfectly, and makes pages with a bunch of videos load fast. Thanks!