Better to go straight to the source [1] (who Hoffmann credits in his video). You don’t need to preheat the water in a separate kettle, you can preheat it in the base. You just need a towel or some mitts for when you screw on the top. The other trick to it is to keep moving it on and off the heat, keeping it at the minimum temperature to keep the coffee flowing gently up and out of the spout, and then stopping it before it gets over extracted.

[1] https://youtube.com/watch?v=u-PeYeiqPLU

I have never seen anyone (here in Italy) pre-heating the water, what may make a difference is that we normally use the lowest possible flame (on a gas burner), in Italy kitchen stoves have typically 4 burners, of which one is very small and in practice "dedicated" to the Moka or to heat very small quantities of liquids, and when making coffe it is usually set to the minimum (actually those caring about it start with a medium flame and then lower it to a minimum, and switch it off completely when about 1/3 to 1/2 of the coffe has come out).

On electric (resistive) stoves the behaviour may be different.