That scene is amazing, but it isn't even the best in the game for me. Mostly because half the criticism of the game is "they railroaded me into doing that, and they tried to guilt me for it", despite the character literally saying beforehand that there isn't a choice, and I think a different scene did a better job of conveying the true theme of the game, which is that the choices you have don't matter in war. I figure a five year old game is fair game for spoilers, so here goes.

It's the hanging of John Lugo. Lugo's character arc was heartbreaking, from a wisecracking sniper to the hysterical conscience of a psychopathic squad, to abandoning even that to summarily execute a non-combatant in cold blood. Eventually, the helicopter crash wounded him, and he was hung by the very civilians he went ballistic for compromising, as Adams and Walker watched. It was gut-wrenching and the instinct is to mow down the refugees who did it. Hell, your team mate is foaming at the mouth for you to. And yet you have the choice not to, scaring them away, and let those civilians die of dehydration instead. It's really my favorite scene of the game, because it proves that even given the right chance, emotions compromise the chance to take it.