It is a brisket in a smoker:
To promote how long they smoke the briskets for their smokehouse brisket sandwiches, they are showing one in a smoker.
It looks like it is resting on a block of ice, and it is folded over. It looks totally unrealistic, as it is the only one in the smoker, and the smoker has a glass window. They are trying to set a Guinness world record for the longest commercial. It is funny for a couple of seconds, and they do have pop up trivia questions where you can win prizes. Check it out so you can say you saw the world's longest commercial.