In the beer refill clip, I am not sure about the minutae of it but there is clearly a cylinder (almost twice the circumference of his forearm) apparent in the early frames on his left arm. As he starts to sit down, the jacket creases in a weird, awkward way. You can see it in other frames as well. It is clearly not his natural arm and I'm assuming it's a sort of beer holster. The slight of hand is impressive though. But what's really impressive is the forearm beer holster. Getting one of those - now that'd be magic.