This is a good video with good advice.
I’m surprised though at how weak his argument is. His main argument amounts to, be careful what you say, because the person you insult might hurt you in the future.
But, what about people who are beneath you? Those people are not in a position where they can hurt you. So, people are free to trash them. That’s actually how things typically go. People typically brown-nose those above them, and don’t speak ill of them, to advance. And they trash those beneath themselves.
"Be nice to people when you’re going up and maybe they’ll be nice to you when you’re coming down.”