So first of all, thank you for creating that course about garbage collection. The videos that I've watched from it so far were interesting and informative to me. (I've completed 71% according to Udemy but I must admit that I sometimes watched videos as I was going to bed and may not have been fully attentive at all times.)
Secondly, a small suggestion for improvement based on the first course: Since each piece is relatively short, it quickly becomes quite tiring that each and every video begins with a ~15 second long intro animation, most of which is just repeating the title of the course. I would skip that all together and make the transition 2 seconds long at most. Just enough to read what the topic of the current video is.