That's a real cool technique, using the weight of the tree to settle on the kerfs, along with the holding wood on the far side to swing it around. It's friggen brilliant! Thanks for posting it!
Lots of in the woods clearance work coming up, I'll be wanting to try it for sure.
I think caution about cutting too deep as you work around to the far side back cut, kind of vulnerable there working at the base of the lean, if the tree lets go before it swings away sufficiently. I think that's why he sets his axe on the ground in the back, as a reference for leaving sufficient holding wood.