There were two things about that moment that made it great to watch live (in person or on TV):
First, there was no play stoppage after the Kings got the ball. Normally on buzzer beaters, there's a timeout and a play drawn up, and as you watch you are getting ready for a make and a win or a miss and a loss. In this case, they got the ball unexpectedly and so the thought that all they had to do was make a shot to win came suddenly.
Second, the ball bounced so many times that time expired and the Spurs didn't have time for one last play. It was obvious that he got the shot off in time, and normally on a layup you are going to leave some time, even a few tenths of a second, for the other team to still have a chance. But with this shot, the buzzer sounded and the red light came on just before the ball went through and you knew immediately that the game was over and the Kings won.
Ahhh.... that was great.