So if I bet the most on either side I can never lose any BTC (and will sometimes win)?
Will be the risk that somebody will make the biggest bet than you and he will return his bet back, but you will lose yours.
So in theory all of the betting should be happening in the very last second of the timer? - where everyone should be trying to bet as big as possible.
Safe explosion occurs everyday. Bitcoins from the safe are divided between the winners, except the largest bet from the loser team. This bet will goes back to the player who have put it. In such a way it's acquires to make big bets. Even if your team lost, there is a chance that you will not lose your bet.
Only one team wins everyday and only the one team, which have collected the minimum amount of Bitcoins in sum takes all the Bitcoins from the stack.
So if you have set the biggest bet in the round then most likely you'll find yourself in a losing team, if someone else sets a bet which is bigger then yours then most likely he'll find himself in a losing team. Ehat would not stop people from making big bets we have decided to return the largest of them.