I don't have any investment in bitcoin-trader.biz. Still I'm amazed at how little creativity detractors show. For example, it is easy to have revolving lines of credit for fiat. There are also multiple ways of moving fait and you can even move by using other cryto currencies. There are fees and spreads that cut into the profit, but that isn't as much an issue if you can trade a multiple of your funds in a day. It is also possible for prices between exchanges to narrow or reverse in a day.
And I'm amazed at how bad the wishful thinkers in this thread are at seeing the flaws in their arguments. Credit isn't free, and you wouldn't get much for something as speculative as this. If you want others to move the fiat for you, you would have to pay fees and they are very unlikely to give you the price for the crypto currency that is required for the arbitrage to work. You are completely ignoring all the real world problems with your "creative" ideas.