What he means by killing it is that it is now frozen at 12:00. In the replica, the 6:00 subdial is directly tied to the hour of the watch. So, at 2:00, the subdial shows 2:00. At 4:00, the subial shows 4:00, etc. In the genuine, the 6:00 subdial is used as an hour counter for the chronograph and thus is always at 12:00 unless the chronograph is being used. Many people freeze that sub-dial so that it appears to be part of the chronograph.