Here is how much torque that is needed to lift or unbend the stake in an axle nut. The axle nut in the video is a Honda / Acura axle nut and the lip is not bent over threads like in this picture from another manufacturer ( I think Toyota) https://goo.gl/photos/WJBCeSk8K2pbU36X7

Here is a picture of the Honda/Acura, you can see the end of the shaft is machined smooth and there are no threads that is where you dent the lip into.
https://goo.gl/photos/MBxjbPJX1Av4FPQk7

The staking is when you dent the metal lip on the edge of the axle nut into the groove in the axle shaft/spindle, this is so the nut does not back itself off. Some believe this can actually provide enough resistance that it will stop an impact wrench or provide significant resistance to turning it with a breaker bar when removing.
After trying it 2 times, the max torque it took to turn the nut and remove the bent metal was less than 20 ft-lbs. Then using a cordless impact wrench set on the lowest setting(setting 1) for this particular model which is 80 ft-lbs it took very little effort to remove the nut.
If your impact wrench can't remove an axle nut it probably has nothing to do if it is staked or not, either the nut is just too tight from rust,corrosion,over torquing or your gun just does not have the power.