His name is Tommy and he also shows how the left arm works in a two-armed swing.
With only one arm, young Tommy uses the Primary Lever of the shoulders with the leading arm.
I’ve talked quite a bit about the whole “stepping into it” aspect of creating massive leverage with the weight shift in the golf swing.
In our last Skype session, which we recorded for WAX Nation, you’ll see how a certain concept worked for Fluffy a.k.a. T. Ferguson with regards to this.