The Cubs are the guinea pigs in this experiment. The Cubs say they're fine with that and the umpire supervisor was in town for it. He says Wrigley Field is a tough place to work and the replay will ensure the umpires get it right.
One of the most controversial calls this season was for the New York Mets in Yankee Stadium. The umpires called it foul, but a fan in the bleachers pointed to the spot where the ball hit the foul pole. Replay would have reversed that call. Cubs' manager Lou Piniella says he supports the replay.
"There's instances where it can help get a play right, I see no reason not to use that resource," he said.
Major League Baseball will make the final call from a room in New York. The umpire crew chief calls from a phone in the umpire room where he can see the video.
It's baseball's first foray into instant replay after other sports, such as professional football, have used it for years. Baseball insists it will be for home run calls only. Len casper says he believes it will be good for the game.
"If you have the technology available, if we can see it when we see the replay, the umpires should have that at their disposal," said Cubs broadcaster Len Kasper.
Another call involved the New York Yankees. The umpires called a hit a home run, despite the interference of a fan in the bleachers who got a glove on the ball. The replay rule is intended to eliminate these heated on field arguments afterward.
"The final outcome is not something that can be debated. When we come back with a ruling from the video replay, there's no argument," said umpire supervisor Larry Young.