A Marine Corps rifle squad reinforced finds themselves in the middle of an ambush from multiple directions. The machine gunner in the patrol reacts by gaining fire superiority.

Priority number one in a gunfight is to make sure you are on the side with the initiative in the fight. The objective in an ambush is to gain the upper-hand right off of the bat, and keep the initiative throughout. This is where the Taliban failed in most of their small unit tactics throughout Operation Enduring Freedom. A majority of ambush attacks by the Taliban were one off, and didn't have the staying power to maintain fire superiority over their opponents, which caused them to in-turn lose an overwhelming majority of their attacks decisively.

What you're seeing here is the perspective of the squad's medium machine gunner. His sole-purpose at the beginning of a gunfight is to locate the direction of enemy contact, and put out as much ammunition as possible to get the enemy's head back down. The fire doesn't need to be supremely accurate to accomplish this goal either. All the gunner truly needs to do is get dialed into roughly the right range and direction, and establish a solid base of fire that returns the initiative to his squad. If the machine gunner happens to down an enemy in the process, that's always a huge plus but he's working with an area effect weapon system.