I agree about these videos not always being designed to get you to a complete understanding just by watching through the series. For example, the 3b1b linear a

I agree about these videos not always being designed to get you to a complete understanding just by watching through the series. For example, the 3b1b linear algebra series is great but I couldn't have used it to become proficient at _doing_ linear algebra. Even having taken a linear algebra class, I got more out of that series as a supplement to actually working out math problems on paper than as a primary source—and I definitely think that's what's intended.