Not sure where HBO is getting it from, but there was something called chironomy (the law of the hand/gesture) that was a part of ancient rhetoric. (See Quintillian, Institutio Oratoria, I.xi.15.)

"No one will deny that such details form a part of the art of delivery, nor divorce delivery from oratory; and there can be no justification for disdaining to learn what has got to be done, especially as chironomy, which, as the name shows, is the law of gesture, originated in heroic times and met with the p191approval of the greatest Greeks, not excepting Socrates himself, while it was placed by Plato among the virtues of a citizen and included by Chrysippus in his instructions relative to the education of children."

It was a part of rhetoric up until the last century ...