Then replace a video with books. If I want to learn something hard, I can Google for the resources on the topic, quickly get the names of books considered the best resources humanity has on that subject, and then proceed to either Amazon or my favourite pirate source. All I can do in 10 minutes to half an hour, and then I can start learning. Contrast with the 80s, where you'd have to go to your local library, which may or may not have any book on the subject, and if it has, it's not necessarily the best.