Anyone ever notice how air bubbles in, or droplets of, low surface tension fluids act very oddly. Speficially i notice they tend to not want to merge and in this case its really weird cause the bubble moves away from the surface as it moves down and the rube narrows. Its likely a sort of cappilary action at play or something.

@freemo i can't help but wonder if i'm looking at your pee in a glass