8:41PM: With 5 minutes left in the second period, Jesper Fast put a shot on net from in close that he thought was in but was not ruled a goal on the ice.
Play continued for another 16 seconds before the horn was blown inside play to stop play. The referee went to the penalty box and was given a headset where he reviewed the play which confirmed that the puck did cross the line.
The NHL war room in Toronto, as part of a rule that was added during the GM meetings in November, "buzzed" down to MSG to stop play and indicate that the puck crossed the line.
Colin Campbell said that they added this rule because a lot can happen in the time where the play happens and the next whistle. (Yahoo)
In previous seasons the play would not be reviewed until the next stoppage of play.
The NHL's explanation of the play:
At 15:27 of the second period in the Buffalo Sabres/New York Rangers game, the Situation Room initiated a video review to further examine Jesper Fast's shot at 15:00. Video review determined that the puck crossed the Sabres goal line. According to Rule 38.6 "In the event that a video replay shows a goal was scored prior to the play being stopped, the Video Goal Judge will inform the Game Timekeeper and Official Scorer of the time and the amount of playing time left to be reset on the game clock and penalty time clocks (if applicable)." Therefore the game clock is reset to show 5:00 (15:00 elapsed time) and good goal New York Rangers.