I have always believed that sharing what you know is very important.
Altruistically, it helps create a wealth of knowledge that anyone can build upon.
Selfishly, it creates a knowledge-base for your future self, and - arguably more importantly - helps you build a following.
After years of pondering on the idea, I took the plunge and started a screencast on React and React Native. I only published four episodes so far, and they are all very basic, but I'm planning on publishing a video every other day for a few months at least.
It's by no means perfect, it hurts my eyes to look at it, and it hurts my ears to hear my own voice, but I had to get started somewhere.
Also, I will be sharing my journey of working on this screencast on the RNcasts blog. If you are interested in starting your own screencast or video course, feel free to follow it. I'm hoping to share all I learn, the good and the bad.