Actually, in the video, his fingers never touch the prop. He grabs the spinner. I do something similar. But I spin the engine backward. I grab the spinner between my thumb and third finger, then snap my fingers. Starts right up and my fingers are never in the prop arc. It generally works only when the engine is warm.
The engine is always started at an idle.
There is a good reason why so many folks have been warning you about reaching around the prop arc. We have all seen people badly hurt. There are very important tendons that control your hands and some fairly shallow arteries in your wrist. If you don't bleed to death, you can still loose function in that hand. And then you might not be able to fly anymore, phooey.
It appears to me that most people that injure themselves do it early on, within the first few years of flying. Its like almost anything that has some danger attached to it. The new guy always gets it.
So, you might see folks like me snapping my fingers and my engine comes to life. But that doesn't mean that you should do the same. You should see me reach for the glow driver. It is a very exaggerated and deliberate movement that I have done for years and could not do it any other way now. But we all have our routine, our ritual that insures we don't get hurt and that the plane is ready to fly. You will need to develop your own. And do it the same way every time. Do things very deliberately and carefully, don't rush, and always be aware of what your doing. Don't allow others to distract you when you are starting up.
That plane could be strapped to a pile of cinder blocks and nailed to the floor and still ruin your day if you reach into the arc. Guns don't kill people. People do. Its the same thing. Just maintain a heightened awareness when you start up.