If you stop the video at :29 seconds, you can see the look in their eyes tells of mental illness. They are addicted to a "drug" and that drug is called Adrenaline. Although the condition is recognized by the scientific community, the term is not yet an official psychiatric diagnosis and, like "sex addiction," the concept needs to be sharpened and clarified through physiological studies.
What these people are doing is activating their fight-or-flight response. Many firemen and police officers also fall into this group. When you activate your fight-or-flight response, your body pumps out other "drugs" (or endorphins) that are similar to Heroin, and like Heroin, they need larger and larger amounts to get the same high. And in the case of Adrenaline Junkies, this means taking bigger and bigger risks.
I'm thankful I don't have this condition.