Can't be knocked back by windblast?

About half way threw the example it looks like the person is hit by a wind blast, but isn't knocked back.

Is this just because the person was in Demi or is that normal for Hail?

He wasn't using Wings of Eclipse so it likely wasn't from Demigod.

Its demi's side effect it has a small chance to give you advance heavy stander for a hit, i have just tested being hit with windblast during hailstorm.