Thread:PlasmoidThunder/@comment-28673060-20161026130007/@comment-3495717-20161027173635

It is explained here. I genuinely can't help you any more than the usage documentation does, though the following are parameters most people use in addition to what's there: If we take as reference and include all three of the aforementioned optional parameters, the YoutubePlayer template would look like this:
 * If you want the music to autoplay, add  to the template.
 * If you want the music to loop (start from the beginning again once it's finished), add  to the template.
 * If you want the player to be invisible, add  to the template.