There are just so many great educational/maker channels, here's a bunch more that are least known on my list (in no particular order):
Not David
iforce2d
Chronova Engineering
Posy
SuperfastMatt
Michael Rechtin
AlphaPhoenix
Hyperspace Pirate
Nicholas Rehm
James Biggar
Casual Navigation
Kraut
Spanning Tree
Geo History
EgyptologyLessons
Carl Bugeja
electrosync
Historia Civilis
Jeremy Fielding
there oughta be
Andreas Spiess