With the fans in the stadia seeing replays on huge screens whilst play is stopped, but the referee being unable to change his decision brings the game into disrepute. Either the big screens should show only the state of play (not the replays & different camera angles being broadcast), or the 4th official should have the discretion to use the replay facility to advise the 1st official (main ref.) to revise his decision.
This is now being used in international Rugby Union, and allows the ref. to review a seen where he was unsighted, or where his concentration was on another incident.
'Taking a dive' following a fair tackle would become much less prevalent if the offender knew that the ref. would stop play and review the incident before deciding where to award the free kick/ yellow card. IMHONigel