I agree, there's a long way for the fuel to get atomized. I would be concerned about have a thin piece of brass fluttering in the breeze, and how long it will take to fail, and having some extra metal going past the intake valves, through the cylinder, and past the exhaust valves without holding a valve open or wedging between a piston and the head.
In the video they would just give the throttle short bursts when demonstrating without the device, and then hold the throttle open longer and further to show the device off.
The effects from the accelerator pump are very short, and only effect the initial opening of the throttle blades while the speed of the air entering the venturies accelerates enough to begin pulling the fuel out of the bowls.