It's easier said than done. These girls have been taught their entire lives to leave when the pitcher's arm reaches a certain spot on the watch dial, such that they leave just when the ball is released; relying purely on the human eye, this is fine. But once you start slowing things down frame by frame, you realize they sometimes actually leave a hair early. Who really gives a shit? Especially in a game where something far more important - the strike zone - moves around inning to inning. If it's imperceptible in real time, there's no way it's affecting the fielders on a hit or conferring any kind of significant advantage (except on a steal).
Don't get me wrong . . . it should still be illegal, in order to discourage runners from playing games as in a hit and run or get a jump to score on a single. But base umps have always watched out for this and it's never been a problem in the game until we started going down to the microsecond. It should be policed with the eye, not replay IMO. I think's that's in keeping with the spirit of the game and the rule.