A lot of things in woodturning can seem baffling at first. Natural edge bowls, balls , making pens.
Once you have done one of seen one there is no mystery.
Another thing about the method Barbara and I use
If you turn bowls and hollow forms
The left side of the ball is the same as turn the outside of a bowl with the opening to the headstock
The rights side of the ball is the same as turning the outside of bowl with the opening to the tailstock.
Turning balls this way using a bowl gouge will improve the curves in you bowls and hollow forms.
You might take a look at the 2010 AAW Techniques I video. Maybe your club has it it their library.
The ball in ball demo show the ball layout, turning the ball, and hollowing the ball.
most people buy the Video for the John Jordan hollowing and Graeme Priddle vessels of the South Pacific demos.
There are three other nice demos too.
Al