Pour a Guinness well and you will have a customer for a lifetime.
Admittedly, a little while after the Guinness was poured and he was just babbling on, I stopped listening. However, if you want to impress people, pouring Guinness well truly is a good skill to have, so you should watch this video.
He did miss one thing, though. A truly talented bar worker can not only give you that perfect head but also can put the shamrock outline in the head by drawing it with the second pour.
But perhaps that comes only in advanced alcohol pouring classes.