I spend hours per week learning on youtube. The strength of it is finding 10 year old obscure videos with gems that aren't covered by big content houses. I've gone hundreds of hours deep into subjects I would not have if I had to pay and sign up and quiz and be quantized. All the while taking ads in the face like a good boy. I've always worried about the day Youtube starts killing (what I think is) its best feature, and I think we are finally there.