Problem: you embed a youtube video on your site and then when it’s done youtube displays ‘related videos’ – and who KNOWS what folks will see! I did this one site for a professional medical group and after the intro video played, literally one of the ‘related videos’ was some dude with 200 joints in his mouth! Awesome.
Anyway, youtube has a bunch of parms you can pass, but Divi (apparently as of this article) does not support those. The video just does not render if you, for example, add ?rel=0 to the URL.
What can you do?
You could obviously host the video yourself, but there are very good reasons to avoid this.
The best option, IMO, is to use the EMBED iFrame code (which pains me to write).
Here is how to do it: