Excellent advice, the fact that he has one arm makes it a lot more difficult than it is.
For real pro can crushing you should stand on top of the can with your foot, balance your entire weight on that foot and thus the can. Then you need to bow down and do a quick push on the sides of the can with your fingers. As soon as the sides are dented the can is unable to hold your weight and crushes nice and flat. Gotta watch out for your fingers though.