How to turn off YouTube related videos
At the end of a YouTube video, you might see a bunch of “related videos”.
When you embed a video on your website, the YouTube player may end up showing your user related videos that are distasteful or offensive.

In order to prevent this, we can actually turn off the feature.
All you need to do is add the text “?rel=0” to the URL being viewed or embedded.
<iframe width="640" height="480" src="//www.youtube.com/embed/bDVz4ZCA4a0?rel=0" frameborder="0" allowfullscreen></iframe>