I've seen a lot of Wing Chun courses like this: https://www.udemy.com/wing-chun-sil-lim-tao-module-1-know-yourself/ that promise you results by watching their videos and doing the exercises they suggest. Is it really possible to learn anything useful this way or it's just a waste of money?
My guess is that it's pretty much pointless unless you also practice sparring with a teacher.