Fancybox only displays one single youtube video. Already no strength .. How to fix it?

Question

YouTube

I'm doing this lesson .
Here is the code:

<a class="popupbox-video fancybox.iframe" href="https://www.youtube.com/v/EnZarUPHX1w?enablejsapi=1&amp;theme=light&amp;showinfo=0&amp;vq=hd720&amp;border=0&amp;autoplay=1" target="_blank" rel="group"><img src="http://webupblog.ru/wp-content/uploads/2015/09/видео-в-модальном-окне-fancybox.jpg" alt=""></a>

This is the code that works. As soon as I replace the video link https://www.youtube.com/v/EnZarUPHX1w with my own, for example https://www.youtube.com/watch?v=jEtvucZTQMQ (just any link from YouTube) immediately a white pop-up window, without video.

What could it be? Already tried a lot.

Answer 1

https://jsfiddle.net/xqns8wjr/1/