This is a short list.  There are many great teachers that I have not included to keep the list small. These are my personal favorites. 

Cory Teaches Music

Ukulele Wine Time

Bernadette Teaches Music

Ricky Somborn

All For Uke 

Cynthia Lin Music

Four Chord Simple

Elise Ecklund   She is only making goofy waste of time content now.  Her old stuff was good. Sad!