The Redskins' HC, Joe Gibbs, like most of the football coaches, called a timeout trying to freeze the kicker. The Bills' kicker is one of the best 50+ yard kickers in the league and he kicked the ball across the cros*****ar but the timeout was called before the ball was snapped so the FG was not counted (good call here). After the timeout ended, the Bills positioned themselves for the long field goal attempt one more time. Then the Redskins' HC called the second timeout after the field goal unit was set. This time the referees drew a flag on his call. Based on NFL rules, a team can't call two consecutive timeouts on the same down or it is considered as unsportman conduct and will be penalized 15 yards.
As a result, the Bills kicked a much easier 36 yard field goal to win the game instead of a hard long 51 yard FG.
P.S: Former Washington team safety Sean Taylor's furenal will be held today. I am still shocked that a young talented player ended his life like that. Rest in peace and hope that violence stays away from sports (though it is unrealstic).