The Tooth and Nail Trick Plus the Explanation

How do you get a nail into the middle of a solid piece of wood? The wood has several protruding teeth but looks solid and in one piece. The nail resembles the stick in a Shish kebab except that it's trapped by the wood. Hurt your tiny brain? Spare yourself the agony, here are the answers - one by Roy Underhill and the other by Joe Greiner.

Something interesting I found out was that this isn't the first Youtube video about this tooth and nail trick. And considering the solution can be found online, I guess the guy didn't look hard enough.

[Source: Tooth and Nail trick - a nail inside a wood @ O Just Me]