When I first started grappling one of the most important things I was taught by my training partners was not to break my fall with my arm. I always wondered why till I sprained my elbow. Lesson learned.
Unfortunately for one of these fighters in the video(no spoilers), he didn’t get off easy like I did.
Fast forward to the 1:10 mark to see the injury. And of course, only watch if you can handle people breaking limbs.