You can cancel 623A and 623B into any ex, including AD. There are two (or three?) cancel windows and they are at the end of each sweeps she does in the animation. The timing is a bit strict so it can take practice to get it down consistently.
Now for applicable use, pretty limited. I've seen a player in jp vids use 623B>AD once but it didn't seem to serve much purpose. I suppose you might make someone do something stupid when they see you 623B from full screen and hit them with an AD as they attempt said something stupid.