... uh...
watching vids like that make me laugh out loud. skinny looking white nerds hitting each other at full force with no apparent reason or description...
In the gym, my trainer used to make me lay in the middle of the ring and then drop a medicine ball on my stomach. Id throw it back hed drop it down again. Also, he used to take it and hit me in the gut with it. I don't know if it helped me take a punch, but since then ive become way less flabby in the mid-section. (which is not a result of the medicine ball, just getting in shape in general.)
Not sure if it helped me take a punch. The best thing for that is to actually spar, because then you are actually getting punched.
Standing there, stiffining up, and getting ready to take punches doesnt improve anything but your ability to take punches when your stiff and standing there ready to take punches.