Another consideration is that we learn things from it because we want to learn it. We are engaged with the topic the instant we hit play because we want to watch it.
Compare that with a high school or college setting where the majority of the class is taking it because they have to - not because they want to. This means that there's no initial engagement and a professor can't call out the student in the 3rd row from the back that is starting to fall asleep.
This can work really well for the people who want to learn it. However, it potentially adds to people who don't want to become competent in the material falling further behind.