My experience is that typing the code for components nesting inside components is not really the big hurdle when designing React views ; rather, it's getting the "layout" part of the css right.
The big value in the video seems to be the simple fact that you have a "Form" parent component where adding a child gives it roughly the right look.
But maybe I have Stokholm syndrome, and forgot how simple it was to hook up in GUI in VB3 back in the days !
Nice work !