Oh god didn't you watch the video?
It takes 5 shots to kill an opponent with a DMR.
The guy wasn't moving for half the fight.
His first four shots take the opponent to no shield as they all hit, he then fires six more but because the weapon has random spread, none of them hit, meaning he loses the fight.
What this video shows about the DMR is that it's incredibly unreliable. It's a luck based weapon. Introducing luck diminishes skill. What's worse is they've proven it's more viable to spam the weapon than to wait for your bloom to reset, so really the fundamentals are all f**ked.