Zenith float-level guage

[Mad Mac]

I am making a guage to get the correct float level in my Zenith1 carby. Richard Tompkins’ video shows a hose coming out of the drain-plug hole below the cap jet, but I am confused by that: If the main jet overflows due to wrong float level, the fuel would surely just drain out of the choke aperture instead of gravitating down into the drain-plug hose. Or am I missing something?