Instant replay is in its second year. The process is pretty well down pat now. But, I have rarely seen it to end a ballgame.
Check out this play:

I think it is funny how the players just stick around on the field knowing the replay is coming. In the end the umpire got this one right.
Stop and think about that for a minute. The umpire got it right in real time. This was a whacker where he had to watch the first baseman’s feet, the runner’s feet, the ball bouncing and then the glove all at the same time. The ball beat him by about 1/4 step. Umpire nailed it.
The bounce makes this a bit harder. Umpires listen for the sound of the ball entering the glove and watch the base. The bounce will often make the sound less pronounced. Again the umpire had a lot of things working against him and wound up making a great call.
Pretty entertaining to see an umpire take off the headset, say out, and then just start walking to the clubhouse.