Quote from NZDSPeCIALISt:
My understanding from what I've read on the Oanda forums (no-one seems to have given a full and proper explanation to date) is that if you are arbing Oanda they will give you a warning to change your trading tactics. Lets say a trader had access to the top data providers (or other platforms to compare prices) and using that info to get into a trade just before Oandas servers and algorithms can process that price change, and then as soon as price moves, you get out for a few pip profits, this they don't like, as you are taking advantage of a system inneficiency and they end up losing money on the transaction. They hedge nearly all transactions, but if you are getting in and out before they can properly hedge, than they are effectively not making the spread. Apparently they have programs that can monitor this sort of (in their words) "naughty trading".
Now if you are getting in early and holding for a "significant" time period (lets say more than 5 minutes or going for at least 5 - 10 pips, different story, you are taking on market risk and you primary profits are coming from taking that risk (as oppossed to your primary profits coming from a broker inefficiency).
What difference does it make if it takes 5 minutes or 5 seconds to hit target? I have not heard of a proper explanation to that question, suffice to say, that they will find out what your intentions are and give a warning to change your trading tactics. At the end of the day it's their platform and they can choose to whom and how they will offer that service.
It very rarely happens that someone is kicked off as if they were to do so that person could be a public relations nightmare for Oanda, and to be successful in arbing them is easier said than done. Better to do it the old fashion way if you ask me.