Wonderful tutorial! Very similar to what DH and his family did when they had a farm. Sometimes, however, especially if they where parting it, they would just skin the carcass rather than pluck the feathers-- made it a lot faster.
I also wanted to mention something a friend told me. Her father used to save the gizzard lining and carefully dry it and then pulverize it to a fine powder and would mix a teaspoon of the powder with milk or something when he had indigestion. It is supposedly almost pure pepsin