I've only seen the video partially but well, playing on PC makes quite of a difference. The mouse helps a lot 
Of course deerber is damnn skilled, but doing that in a console is a bit harder. It's usually harder to aim in a console. Also the screen rotation is not as fast in a console.
Now, regarding the video. I saw him nova cancelling mostly in objectives, mainly in pizza. Which makes sense.
I also saw him using reload cancel very well. Quite important on a Claymore.
The weapon is an important part of a vanguard (pretty much any character aside adepts/engineer). Being able to one shot mooks helps a lot. With my Katana, I can one shot weak mooks if I'm point-blank. He was one shooting people at 5 meters.
Nice vid. I really like the vanguard but unfortunately playing off host kind of suck.
ME2 vanguard is even cooler with OP slowmo 