I stay away from using the "brushing of the hands". It's just not a proper mechanic.
Question: On a play where the defender tips the ball from the front court into the backcourt, and the coach is yelling for an over and back, I have seen this "brushing" to let them know that the ball was tipped by the defence. Is there a better way (nonverbal) to let them know that you are on top of the play?