Some Machining related channels on youtube:
this old tony, Chronova engineering, cylo's garage, inheritance machining, breaking taps, blondie hacks, tarkka, dan gelbert, Jonesey Makes, Eric(with a K), Clough42, Alec steele, NBR Works, Not An engineer, Stefan Gotteswinter, oxtoolco, ROBRENZ, MrCrispin, Clickspring, Artisan Makes, MH Anything, Jellyfish machine,Maker B,
And also there is great course on precision engineering by Alex slocum:
https://m.youtube.com/playlist?list=PLksE8LDXGXl_MQHKr2DqhfD...