It is the level of following the reference examples with the minimum basic contents of Spring Security. It feels more like watching a video of a knowledge sharer studying security for the first time than listening to a prepared lecture. If you want detailed theory and practice of security, I recommend Jeong Su-won's course. It is the same price, but some lectures are 21 hours and some are 8 hours. It seems that the knowledge sharer is famous, but most of the lecture contents are reference summaries.