I guess its turning but can you call that a lathe?!?! Ooooff i would not want to get a catch hollowing out the inside of a pool. That man doesn't need a face shield, he needs a helmet and armour.
There are videos of that one and some other monstrosities but I couldn't find any good ones quickly. I have a jet bench lathe I think it's rated for 10 inch swing but I don't turn usually turn anything more than 6 maybe a rough blank might get over that but I usually cut the corners down on the band saw first if it's that size.