This comment is on point. I am told that many students on Udemy use videos courses as a reference, where they skip through videos to find the exact content they are looking for. I'm sure people do this, but I don't think its an effective use of video teaching.

My goal with videos is to show the entire beginning to end process of building some arbitrary app. Many commenters here on HN are advocates of apprenticeships for learning tech; I view video courses as an easily distributable form of apprenticeship.