MediumRoastSteam He does say at 4:35 that it doesn’t have a heat exchanger (“… unlike a single boiler semi-automatic or heat exchanger I don’t need to purge water or even flush to warm the group head …”), so it sounds like it is a termosyphon connected to the boiler, and brew water comes from the boiler too. If the boiler is at 1.2 bar (3:31), this means boiler water at 105 °C, which is hot, but still tolerable since there will be a few degrees of loss until the water reaches the coffee. It’s kind-of-a-saturated group…
Judging from the cap on top of the boiler, there is no pump, connection to mains or anything - just wait for the boiler to cool, and fill it with fresh water.