Makey:
Adam Savage's Tested - Random making and VR hardware reviews
Simone Giertz - Builds shitty robots
Primitive Technologies - Makes things starting with just his own two hands and some lovely wilderness.
Clickspring - Remaking the Antithykara mechanism, referenced before.
Mathy:
Numberphile/
Numberphile 2 - Random mathy things
Vi Hart - Random mathy things
Standup Maths - Random mathy things
Singing Banana - Random mathy things
Other:
First we Feast - fun celebrity interviews while eating progressively hotter wings.
Accused Farms - Computer game-related content and commentary
OskarPuzzle - Makes puzzles
Cyriak - weird