Firearms accidents happen to everybody. The gun handling professional in this video is just discussing how not to play with guns when it goes off. It is a Glock 40 and it appears he is speaking in a classroom setting with children present.
This video does not show blood and guts, but demonstrates a lesson to everybody about gun safety. He even appeared to check the chamber and have it verified by another adult present. It still fired into the floor. At least he had it pointed in a safe direction!