Ndoghouse that sounds too much like what we did too. We grew up near Berlin (Potsdam) in a big apartment complex which was built on the edge of a forest. Nobody played on the playstructures. Everyday was forest time.
We also dug out rooms and connected them. The soil there was lose so that it was easy to tip over 12 foot needle trees which we used to cover our trenches and sometimes we simply covered some old bomb craters. Was lots of fun, except for the occasional hornets nest. Once a friend found some old WW2 hand grenade, the one with a stick. Even discovered a bit of silver which some must have hidden before the Russians came.
The video is pretty cool. Definitely a Kukri!! I wish I'd know how long he took for everything. Just making the hut would take me a day at least without any help.