Hi @dcooney, thanks for your reply. It’s creating the correct code:
<a id="5e30bf109cce9" rel="wp-video-lightbox" href="https://www.youtube.com/watch?v=viAKw09TJSk&width=640&height=480" title="">Play Me!</a>
But it just links to the Youtube page/URL and it’s meant to open a lightbox on the same page with the embedded video.