I've seen this one before and I must say that it's a safe way to do it on a 6th Gen Accord. Why? I have a 6th gen Accord
and they are prone to trans failures (seriously, have seen so many of them with ruined A/Ts at certain mileages.)
I have learned my lesson and I'd only do the drain and refill by hand, using genuine Honda ATF. And, yes it will require a little more
trans fluid.
A flushing machine will force transmission fluid through the tranny at low pressure. So this could harm your tranny.
I think doing it manually is safe for the long run. I'm only saying this based on what I know about Hondas, maybe, it's a different
story for a Toyota .