That Marine standing at attention is probably grateful Uncle Joe can’t read minds. You can just imagine what he’s thinking about our stumbling, bumbling, tumbling President. But he has to keep a Poker Face anyway.
In all seriousness, I've spoken to a few in the military who were on duty years ago at various times when prior presidents walked into the room. Without exception they say that when he walks in they don't see a corrupt politician who breaks his promises like the rest of us see. All the serviceman sees at that moment is Commander-in-Chief.
I won’t be surprised if they watch the videos and find out who was laughing, and those folks will get a nice visit from the FBI.