Also at your link:
A soldier firmly requests that the crowd "maintain a level of silence and respect" at the Tomb of the Unknown solider because some people were laughing disruptively. He didn't yell but he certainly made sure his voice carried to the audience.
Tomb of the unknown - soldier yelling at laughing crowd
Most often the “disrespect” is inadvertant and due more to ignorance of proper decorum...To the Tomb Guards however, because the Tomb is a sacred place of honor that all are expected and will be required to respect, they are serious as a heart attack about their mission...This is NOT theater for the benefit of the public; it’s real...
People tend to believe a display like the Guard made in the vid is all “for show” and usually it is, because most often that’s all it takes...But the rifle is a fully functional M14 (he qualified with one), the bayonet is real (and he knows how to use it), and a Tomb Guard is fully authorized to get physical (and it has happened) with anyone attempting to desecrate The Tomb...A butt stroke with an M14 is not something I’d ever want to receive...
Then arrest by Arlington Police follows...
From a former Old Guard troop...Never walked “the mat”, but had friends who did, and I’m proud to have served in a line company...