"Top rudder" is when you apply rudder towards the outside of a turn. So in a right turn you'd apply left rudder (called top rudder becaue you are pushing with the leg that is at the "top" of the aircraft.) The instructor in the OP suggests applying top rudder in a steep turn to keep the nose up. This is a load of crap in my opinion. Top rudder will put you out of balance which increases drag which degrades performance which is the last thing you want in a steep turn.