Defining The Kilogram

This guy starts off being a little too glib, a little too cutesy, but he gets better as he goes along, or maybe I just got used to him. Only problem I see here is how they know it's a perfect sphere? Yes, they measured the diameter, but do all the diameters intersect in the exact same location? And did they stop when they got to perfect roundness, or when they got to the right weight? Supposedly they arrived at both at the same time, but how did they manage that? Yes, I know, I am picking nits, but they are the ones squabbling over the weight of a fingerprint, or a grain of rice. A grain of rice has to weigh more than a fingerprint, doesn't it? I guess it depends on how greasy your fingers are.