In the video, it said that the call was flashed on the scoreboard as well, so everyone in the stands would know what the correct call was. Regarding home team adjustments, have the technical person be an employee of MLB and part of the umpiring crew. More ump jobs may be a way to keep the umpires happy. Regarding the close calls, tennis is able to figure it out. I'm sure they can, or do use, similar technology with the strike zone. Even if it's slightly off, it will be off consistently which is a huge improvement over what they have now.