Here is what confuses me with it. Say the military guy picked out a sign -- those calls are coming within seconds of the ball being snapped. I know we had 3 people giving signs at the same time and we weren't anywhere near the D1 P5 level. This was before all of the technology now available, so teams are even more secretive about their hand signals, using signs, etc.
It is way above my pay grade. Best I can think is he could say to the DC, i think it is a pass or i think it is a run. You'd have to know the playbook of the opposing team to know exactly what plays are being called from the sideline.