---------------- HTML ------------------

<a href = "http://www.youtube.com/embed/BLQFAUvwWrk?autoplay=1&amp;rel=0&amp;autohide=1" class="video_pop_up" rel="galleryVid">
<img src="http://img.youtube.com/vi/BLQFAUvwWrk/0.jpg" width="370" height="250" />
<span class="play">&nbsp;</span>
</a>


---------------- CSS - For adding a play button to the video thumbnail ------------------

/*-- VIDEO PLAY BUTTON --*/
		
	a.video_pop_up {
		position:relative;
		display:block;
		}
		
	a.video_pop_up img {
		position: relative;
		z-index: 5;
	}	
		
	.play {
		width: 74px;
		height: 73px;
		background: url(/furniture/images/buttons/playbutton.png) no-repeat 0 0;
		position:absolute;
		top: 80px;
		left: 143px;
		z-index:500;
		opacity: 0.8;		
		}	
		
	.play:hover {
		opacity: 1;		
		}



---------------- FANCY BOX FUNCTION ------------------



	$("a.video_pop_up").fancybox({
		'speedIn'		:	600, 
		'speedOut'		:	200, 
		'width	'		:	800, 
		'height'		:	400, 
		'type'			:	'iframe'
	});

Add a Youtube video to a page with a dynamically generated thumbnail, when the thumbnail is clicked open the Youtube video in a jQuery Fancybox modal window. Auto play the video and hide related videos at the end

Youtube Video in Fancy Box pop up with Thumbnail

HTML