Disclaimer: I have no dog in this hunt, at all. Don't care which team got the better end of this deal, or who won.
I went back and looked at it in stop motion, frame by frame, and there is daylight between the A player and the ball all the way. He never touched it (or, it never touched him, however you want to look at it). But, it definitely deflected off the B player's foot. The ruling on the field, and the 'stands' ruling by the RO are righteous (although I would always prefer a 'confirmed' ruling when the evidence is this clear, IMHO).