Ok, I'll be the first. Here are some of my favorites to watch...

Robert Murray Smith- https://www.youtube.com/user/RobertMurraySmith
(He does an awesome job showing how to make Graphene and use it to make super-capacitors)

ZeroFossilFuel- https://www.youtube.com/user/ZeroFossilFuel
(His series about HHO generation and the Rocket Stove are my favs)

Mr.Teslonian- https://www.youtube.com/channel/UCVP1PTBbRGpmTQE1oQx8xNw
(This guy just does some all around cool stuff. His trompe video reintroduce me to the power of compressed air)

I'll list some more later :-)