That’s an interesting way to do it, the butter too. We gave the video a look.
The wife said she has grated and does a twice rinse. I only grate (with skin, its the best part!), squeeze, and cook! 
Honestly, I typically just throw a little butter in the pan and olive oil. I cover sometimes, and yes, cast iron! 
Thanks for sharing Kay!
P.S. I think I’ll try both methods next time and see what we like better.