I saw the same thing. IMO when braid is tied directly to the spool it can "slip" and your line will start to spin on the spool as if your drag is loose. Unless they are putting a small amount of mono, then braid... im not sure I agree with this
I always back braid with mono to prevent slipping. So Like you said one would have to put mono backing, braid backing, then working line (mono, braid or floro).
One of the reasons he does it is to get longer casts, because the spools spins faster. However, I use the brakes to slow down the spool, so I doubt that benefit would apply to me.