I am not really sure of the current set of rules concerning monetization of YT video boundaries are, however if you are using the video as a point of commentary under the "free use" terms you can make revenue from it via various means. Many of the content creators there make (better) money after achieving a certain level of viewership from which then the platform takes on corporate/company sponsors and perks. Some of the benefits are tangible goods they get to keep.
I am sure there are readily available terms somewhere on it and there are also many videos related to the content creation process. My own understanding of it being a LOT of time, hard work, skill, and charisma.
"without their permissions " is not necessarily true.
Yes, I've seen a lot of these.
The original videographer uploaded it to "somewhere". Youtube.
Possibly giving up future ownership rights. (i do not know if this is true)
But the entity that compiles them and uploads a thing of 20 of these shorts may or may not be giving a kickback to the original entity.
But it is also incumbent on the original entity to push back and enforce his copyright if he wants.
But they may not want to, because the short video clip of their friend doing something stupid is getting FAR more exposure than it was on its own. Which is what they wanted to begin with.
People can "earn money" with this by really good at compiling these, and gaining a following.
Lots of clicks on utube == "money".