That was my first thought as well. Fire off three or four rounds with the stock in that position and I supsect you will not be using that shoulder for the rest of the week.
Also did you notice that he is firing almost parallel to the ground? Aren't skeet tossed into the air? Whatever he is shooting is no more than about 10 feet off the ground.
Also shouldn't a skinny guy like Obama be wearing a shoulder pad? He's just wearing a polo shirt.