[https://www.youtube.com/watch?v=Nb1lMgQluZQ?rel=0]

if you add ?rel=0 to the end of a youtube video it will only show related videos from the same channel. It used to remove related videos altogether, but YouTube changed the way it works.

It is most useful if you are publishing unlisted videos, there will then be no videos shown at the end.

The Embed Plus for YouTube plugin can help with a lot of youtube issues.