No, it's not the infamous miscalling of Florida; it's actually MSNBC's calling of Gore's victory in Pennsylvania.
There are a number of reasons why I describe it as amazing:
Listen to Brian Williams' tone. He strongly implies that it's basically over and Gore has won.
At around 39 seconds you can just see Chris Matthews shaking his head as the camera cuts back to him. He has stated that he voted for Bush in 2000.
And, most notably, Ed Rollins says outright that the election is over, "unless there's some hidden vote that we haven't seen". Then he says that "Bush may win the popular vote and lose the electoral vote".
http://www.youtube.com/watch?v=i7GD8On7aQU