Have you ever looked back at an old text message for the link someone sent you, or the name of a restaurant. Annoying isn't it. It's the same with facebook, you see a funny post and then spend ages trying to find it again to show to someone else.
Videos aren't like this, youtube is set up to be searchable, its the second most searched place on the internet behind google, so when you create a video it stays about. If you spend £200 on facebook ads or in a month your money has done its good. If you create a video put it on youtube and link it to your website then that gift keeps giving.
I have clients who got into video 2 years ago and still get rewards from their early videos. They are still making them money.