I teach mathematics and I use my own videos. Students supposed to watch it and then we use the class time to practice the topic. Many students eventually appreciate this. However, some ask me "Why can't you just lecture us in class on what's on video?" So... after all my work to make the videos and prepare the in-class problems and activities, some students complain that I am really not teaching them as they have to learn everything on their own. I think these are the students who are surprised that learning must happen on their own anyway, either it is outside of the class or in-class. I can see why coming to a regular lecture class can be easier for a student than coming to an interactive thinking and solving problems class. But, is it better to just listen to the in-class lecture and have hard time doing homework at home, or learn how to solve problems in-class with the help of peers and the instructor and then watch the video for the next class at home? There are always two groups of students, those who like the particular style of teaching, and those who don't. I'm not sure how to satisfy both.

I would be very careful with using videos of others. I spent hours watching various videos on a particular topic before I chose a suitable one for my sabbatical project. Generally, the YouTube videos of others may not be aligned with what you want to teach, maybe of poor quality, or even contain some errors. I had a student who signed up to the Math Tutor site, thinking that this will definitely help him. Then, on a test, he answered all the trigonometric questions that referred to special angles (they required an exact answer) using a calculator. Since we were never using a calculator for these type of questions in class, I presume the Math Tutor site was teaching him that way.

That being said, making your own good quality video takes a lot of time and energy. So, I guess it depends on what you want to achieve in class by using a particular video. If it is an instruction, I would probably do it on my own. If it is just a refresher, expansion, or a base for a class discussion, I can see using videos of others but carefully chosen.