How to displaying a Vimeo video in a Lightbox that launches with the page load

jQuery Video Lightbox

You can try the jQuery plugin HTML5 Lightbox: http://html5box.com/html5lightbox/index.php, the quick installation is here: http://html5box.com/html5lightbox/index.php#quickinstallation

You can add the following code to your webpage head section, just before </head>, and must be after the html5lightbox.js code.

<script type="text/javascript">
	jQuery("document").ready(function(){
		html5Lightbox.showLightbox(4, 'http://player.vimeo.com/video/1084537', 'Big Buck Bunny');
	});
</script>