Good video. Looks like they were working on Fagus sylvatica??Odd when i see the 'gob' cut being started on the horizontal. Commencing on the vertical means you can see when the horizontal meeting the vertical, true front hinge everytime. Finishing the fell, i was taught to come down on an angle as it keeps you in a safe zone incase the last splinter pings back. Difficult without diagrams. Perhaps if rot is suspected, gob can be cut before buttressing to give you a better idea of the extent of rot. Retained buttresses could help with an angled fell?
Just ideas, basics in vid i think were sound.
Cheers
