Glad you are enjoying the videos!
Most of the time in a Video series is in the prep - what to teach, what we will make, making sure the content follows best practices etc..
Each series is different - to give you an idea Flexbox.io took ~40-50 hours. ReactForBeginners.com took 200 hours. LearnRedux.com took 100 hours.
I'm slowly transitioning myself off client work to work fulltime on teaching - that is through videos, books, in person at HackerYou and WorkShops