Best electronic video blog ever
https://www.youtube.com/user/EEVblog 

This is how things should be thought in school:
https://www.youtube.com/user/crashcourse 

All that maters explained in simple but hilariously fun way:
https://www.youtube.com/user/CGPGrey 

Things about materials around us, arranged around Periodic Table of the Elements:
https://www.youtube.com/user/periodicvideos