i'm 100% with you fancy. a good video replay system would only take a couple of minutes, and i'd rather a 5 min injury time with the result determined by reality than a 3 min injury time with the result determined by referee error. limiting the situations where it can be used to the box and to once per game means that coaches have to be careful when to use it.
but the best part of your post is the after-game review of diving. the red card on kaka would be rescinded and that joke of a diver suspended for at least the next game. that kind of garbage ruins the reputation of the game. it needs to stop. your solution doesn't slow the game down at all, but if these pansies risked missing games for their fakery you'd have to think they'd step it down a few notches.