It seems to me that you think that the Bet address on Roulette table is unique for each player? If that's what you think, then you are wrong. The address is always the same for the same bet. All the players use the same address. Players don't need to register accounts to play Roulette. That is why the prizes are sent AUTOMATICALLY to the same address the bet was made from. In this scenario it would not be enough to simply ask Bitplay BTC deposit address.