I can't put a video up, but it happened about 02:06 left in the 4th quarter. Replay of the incident is with 01:44 left. (Mihocek missed a set shot)
Salem came in from the side to pressure/tackle/knock out the ball off Harrison. To me it looked like Salem hit more with his forearm and has just winded Harrison, Salem did have a clenched fist but I'm not even sure his fist connected, as Salem's arm was swinging sideways. Looked absolutely fine live, but you know what slowed down footage looks like.