Lightbox youtube video example: HTML:
<a class="popup-youtube" href="http://www.youtube.com/watch?v=0O2aH4XLbto">Open YouTube Video</a>
Then in the JS (can be in the file js/custom.js) you add a call to the lightbox plugin, like this:
$(document).ready(function() {
$('.popup-youtube').magnificPopup({
disableOn: 700,
type: 'iframe',
mainClass: 'mfp-fade',
removalDelay: 160,
preloader: false,
fixedContentPos: false
});
});
For more information you can see the plugin documentation: http://dimsemenov.com/plugins/magnific-popup/