Depends on how strict they are. Some play safe where a brush scores, or punching to the side of someone's head(instead of contact with the head), things like that. I believe a lot of it is being afraid of injury/lawsuits.
I participated in the point-stop portion of a Yoshukai Karate Tournament 2 years in a row. The first year they had no rules for too excessive contact ("If you get hit and lose your breath, you're not training hard enough") except in the face and they only called good, clean shots. The second year they started calling lighter/less clean hits. The third year I only watched and they used the "punch next to the head" rule, which was quite disappointing, but there were still some good bouts.
Stamina..not really, although my exchanges lasted longer than the video you showed. Don't know if that means I was better or worse...
To sum up, it depends on the rules set forth by that particular tournament/organization.
We should all take ourselves seriously...and then crumple that image up and toss it out the window.