You really don't have much unless you can show nearly 100% correlation: when she scratches, Holt does one thing -- when she doesn't scratch he does another.
Otherwise, it can be chalked up to a nervous tic.
from the article
...During the debate when Clinton wanted to signal Holt when she wanted the floor, she rubbed her face in a manner similar to a baseball manager.
According to True Pundit she has not done this in any other debates during her career supporting the accusation that these were signals.....
Lots of people have nervous gestures like that; and I can’t remember her performance back in 2008. But I haven’t seen those gestures in recent videos...