Well. A bottle is topologically equivalent to a solid sphere. It only has one surface. The inside and outside of a bottle is just by convention. Usually you wo

Well. A bottle is topologically equivalent to a solid sphere. It only has one surface. The inside and outside of a bottle is just by convention. Usually you would say something is inside the bottle if it is past the opening. (As he says in the video.) So your example with the bowl-shaped "sphere" is correct. There's no clear limit when a bottle has an inside and an outside.