Lvl doesn't matter in that kind of sense.It's about your gear. It comes down to Dmg output and defence. If you're a higher lvl you have more defence and your output on dmg is much higher than lets say a lvl15. Lets take factors into consideration. 1.He has friends helping him against a 6man group of RANDOM people. 2. His friends are shooting the same target. 3. It takes a whole clip and some more to even kill an enemie. 4.If you have watched the video you would notice the people on the other team missed alot of shots(Warlock he killed in the first 30seconds missed a melee attack) 5.He is also using cover/camping which is not bad but you must also take this into consideration.