I have no idea how many tennis videos I own. I have a six foot banquet table stacked about 2 feet high with tennis videos. I have learned a ton about tennis from these videos. I still get instruction from competent instructors, but there are tons of things you can learn from videos.
Here’s some of the places where I shop for videos:
Fatso Tennis (hahahaha. I had to slip that one in)
Get busy learning from videos