I heard that this guy was cheating so I found the server he was playing on and spectated him. He was using a U-100 MK5 LMG to kill people through walls, shoot out heli pilots across the map and kill people that were not visible to him.
I'd like to thank EA and DICE for implementing the "Game Time" feature, which allows these cheaters to cheat without even purchasing the game, they can make unlimited accounts and cheat on them all. This particular hacker said "I play free", just like 99% of the hackers do, thanks to the "Game Time" feature.
Currently, Sergeant_Sneaky has 71,891 views for Battlefield 4 across 377 videos. This game accounts for over 1 day of watchable video on his channel, roughly 46.72% of Battlefield 4 content that Sergeant_Sneaky has uploaded to YouTube.