https://www.tuinland.nl/js/production/libs/media-slider.js

1var curr_media_no = 1,
2	max_media_no = $('.media-gallery-slide').length;
3
4function showMediaItem(media_no){
5	if(curr_media_no!=media_no){
6		if(media_no > max_media_no){
7			showMediaItem(1);
8		} else if(media_no < 1){
9			showMediaItem(max_media_no);
10		} else{
11			var currentMedia = $('#media-slide-'+curr_media_no),
12				nextMedia = $('#media-slide-'+media_no);
13			
14			nextMedia.css({opacity: 0}).addClass('active').animate({opacity: 1}, 1000);
15			currentMedia.animate({opacity: 0}, 1000).removeClass('active');
16			
17			$('#media-thumb-'+curr_media_no).removeClass('active');
18			$('#media-thumb-'+media_no).addClass('active');
19			
20			curr_media_no = media_no;
21		}
22	}
23}
24
25$(function(){
26	$('.media-gallery-slide').css({opacity: 0});
27	$('.media-gallery-slide.active').css({opacity: 1});
28	
29	$('#media-gallery-prev a').click(function(e){
30		e.preventDefault();
31		
32		showMediaItem(curr_media_no-1);
33		
34		$('.youtube-iframe').each(function(){
35            this.contentWindow.postMessage('{"event":"command","func":"pauseVideo","args":""}', '*');
36        });
37	});
38	
39	$('#media-gallery-next a').click(function(e){
40		e.preventDefault();
41		
42		showMediaItem(curr_media_no+1);
43		
44		$('.youtube-iframe').each(function(){
45            this.contentWindow.postMessage('{"event":"command","func":"pauseVideo","args":""}', '*');
46        });
47	});
48	
49	$('#media-gallery-thumbs a').click(function(e){
50		e.preventDefault();
51		var getMediaId = $(this).prop('id').replace('media-thumb-',''),
52			thumbOptions = $.extend({}, eval('('+$.trim($(this).attr('rel'))+')'));
53		
54		showMediaItem(parseInt(getMediaId));
55		
56		if(thumbOptions.isVideo){
57			$('.youtube-iframe').each(function(){
58                this.contentWindow.postMessage('{"event":"command","func":"playVideo","args":""}', '*');
59            });
60		} else{
61			$('.youtube-iframe').each(function(){
62                this.contentWindow.postMessage('{"event":"command","func":"pauseVideo","args":""}', '*');
63            });
64		}
65	});
66});