I fixed my fridge by watching a howto video online, but that's nothing compared to what Asmelash Zerefu of Ethiopia did: He built an airplane by watching YouTube videos.
Zerefu has always wanted to be a pilot, but in 2001, he was turned down from the Ethiopian Airlines Aviation Academy because he was about half an inch too short. But that crushing setback didn't deter him: Zerefu decided to build himself a plane from scratch.
Jonathan Wells of The Telegraph has the story:
... following ten years of planning, the day arrived that Zerefu had to begin construction on Ethiopia’s first ever home-built aircraft. After incorporating the design of the Clark-Y Airfoil Wing into his own unique plans, and tailoring other existing plane parts, Zerefu began the long and arduous task of sourcing the components and materials he would need to construct his very own magnificent flying machine.
"I collected from garages and workshops, and Merkato - which is Africa's largest market - in Addis Ababa. I used first and second-hand materials to build my aircraft.”
Did Zerefu succeed? Read the rest of the story over at The Telegraph.