Around 1:37, something happens in this video for which the person is penalized. He apparently "checks behind" when he is not supposed to do so. My question is to explain this situation and why it's illegal without poker jargon.
Apparently it's because this person has the "nuts" or the best possible hand from the community cards at the river, and he is not allowed to check. Does this video mean that if at the river you have the best possible hand it's illegal to check you have to raise? Where is this enforced if that's the case.