If the bookies are on the ball, they'll make roughly the same amount of money whoever wins, because they should "hedge" (that is, have a similar bet with another bookie) any large bets that mean they might lose.
What can stuff them, though, is any large bets placed very late on so they can't pass the risk on. So, when you're watching the prices change, if the odds are reducing (e.g. going from, say, 10/1 down to 2/1), that's the event the bookies don't want.
K