It is great to see such perfect control of a most effective tool. But I use the spokeshave as a finishing cutter. It takes too long to remove the bulk wood, so I use a razor sharp draw knife, bevel down, to get those corners down and shape the buttstock and lower forearm.
Watching grain direction is imperative, of course, and you still need to use a lot of control. Otherwise, you could get into trouble fast. Shaping a butt this way takes only minutes.
You can see by the size of the shavings on the floor that the wood came off fast, but accurately. My spokeshave is an iron Stanley, and I agree that it is very effective. I'd like to own a pretty wooden one like the op has posted.