The dynamometer in question can only read up to 2,500 horsepower. Past that the chart simply flatlines, meaning the car was making far more. The final output of 2,719 was determined using a formula based on the car's torque output. That's more than five times a stock GT-R's output when it first debuted in 2007. While that much power is completely unusable on the street, this car was built purely for drag racing.
The video itself is rather entertaining to watch. The driver quickly pulls up a few gears, before going deep into the accelerator. The nose lifts and tires start to flex. Think top fuel dragster. It's difficult to hear the exhaust note over the high-pitched turbo whine, but several seconds in, the car coughs, spitting out a few flames and rattling the surrounding tool boxes and cables, possibly breaking the television. At least ETS unplugged or removed the car's airbags.