Not quite sure where this person is getting their frame data from. Her juggles ending with 6PPP to ground throw leaves her at neutral as I mentioned before. I tested this in the past so the throw whiff basically recovers around the same time the opponent recovers from the quick tech.
I tried the wall splats here and I was still left in negatives, mostly -5 with the lowest being -2. Maybe someone can replicate the uploader's results, but that's what I got :/
*Edit: Messed around with the wall splats some more. I guess I was doing 6T too slow. It looks like you have to do 6T as quick as possible and wait for a split second before going into her low/ground throw. While doing the low/ground throw as quickly as possible will put you at a small advantage when they tech regardless if you wait that split second, if the opponent chooses to just lay there, you'll end up with just a whiffed low throw on a grounded opponent instead of a ground throw.
**Edit: Ok, so I tried it with more characters and in different stages and it feels inconsistent :/. Even when I record Tina to do the whiffed throws the fastest possible, I was able to jab out of it. Maybe you'll have better luck with it Sly