Coaster brake: concave sprocket orientation The sprocket for my coaster brake hub is shaped concavely in the middle, it is not symmetrical.
I've seen some people on Youtube who had it mounted on the hub facing inward, and others facing outward.
What is the purpose for this concave shape? What is the correct orientation?
(My guess is that you can flip it around to adjust the chain line, but I'm not entirely sure)

Video showing my hub:
Your guess is right, it's a way of dialing chainline. Most commonly you use it in the more outboard position. It's easy to just measure front chainline and both rear chainline options and see which position is optimal.