How a cup of coffee is made in Turkey

The sand is hot and is being warmed by a flame underneath. Coffee and water is put into the metal container and is boiled using the sand to conduct heat. The "filling" you see is just the coffee (which is thicker and stronger than american coffee, due to the grounds being left inside) is just the coffee boiling up. The turkish use sand because it is easy to control the amount of heat being transferred into the coffee.

But... he's pouring the same container out each time. I'm confuzzled.

he doesn’t pour it completely until the end

It's a bit tricky to see while he's pouring, but if you compare the end amount of coffee in the cup to the size of the metal container, it matches up.