The man in the bubble in Yellow Submarine

In one part of the Beatles’ movie Yellow Submarine, there is a bearded man in a bubble. Later, he holds up a watch (I believe this is at the beginning of the “Sea of Time” scene). If I recall correctly, he looked like he was drawn using that process where the animators trace actual film (what’s that called again, rotoscoping?). Who is that guy? Was that clip done specifically for Yellow Submarine, or is it from some other movie?