The pad looks like a Jostam Anti Flinch but could have been a period mod as they were available even way back in the '20s.
My bet is that it was added later when the scope was mounted.
He states that the sights are not original but, of course, if you can't hear him on your computer you didn't catch that.
Still, great to see a classic out hunting and performing as well (or better) than most modern rifles.
Dang near a century old and surely well capable of going another easily.