Idk if that is actually possible (correct if I'm somehow way off), as the person clicks on the air when placing a block. That's not pure skill or experience, that is just clicking on empty air and somehow placing a block because of it. Slowing the vid down to half really shows it as well. Not sure how you could really learn that xd.
It's difficult to do with any consistency, but it's possible to put your cursor in the exact right place to set blocks in front of yourself as you move without an anchor block on the cursor. I believe you might only be able to do it when you hold the place button, manual taps probably don't work.
This only works for me in Bedrock if you are standing on the last block and then place the next block moving in the direction of build. I am not as fast as this guy because I tend to stack slower than I walk and then I fall into oblivion.