As you can verify in blockexplorer, this pool does all payouts without transaction fees. To do this, they include all payout transactions in the the blocks which the pools *itself* mines (because other miners might discard the transactions because of missing fees).

So if 50BTC pool finds no block for 5 hours (which is bad luck but possible), the transaction will not be confirmed for 5 hours. You will have to wait until the next block is found by 50BTC (http://blockchain.info/blocks/50BTC) until you will get your payout.