The best learning sites take care to plan out how much content goes into each video as well as the sequence of videos.
Videos can be standalone, although usually, they're part of a series. A course might contain several hours of videos, but they're always broken up into parts. The best learning sites take care to plan out how much content goes into each video as well as the sequence of videos. In this way, your learning is cumulative. You're typically building new ideas or concepts on top of what you've already learned.