They are using different gateway, other known gateways are hitbtc-payout and hitBTC-exchange, there is payin, you can follow the money flow with hitBTC-exchange account, and you probably have a point with the SBD/BTC market pair it joins around at times with some crazy numbers, not to sure its entirely correct myself but I can say, there are traders trading that pair, its a favorite in the trollbox
RE: Why Is SBD Getting Dumped Like This?