I don't know why everyone is so down on Sodajerk.
The strategy he mentions is very old and very well known. Several big time traders in the Market Wizards book used the exact same strategy, whenever different marketplaces would diverge.
Since the divergences are somewhat random, you take your profit by waiting for a chance convergence, or a divergence in the opposite direction.
However, there are several problems at the retail level.
1. Some of the people that have used this strategy in the past actually had a way of buying something (a stock, or a futures contract) in one market and then selling it in another. The actual trade only lasted seconds and only incurred two commissions. I don't know the details of how that is done but I know that retail traders can't do it.
2. I think it's unlikely that the divergence would exceed the spread, although I don't really know. I understand that forex spreads are pretty wide.
3. You've got to overcome the spread again when you take your profit.
4. As a practical matter, you've got to have the ability to simultaneously execute before the divergence disappears. You'd probably need a custom computer program that can interface to two different brokers simultaneously.
In short, it's a good concept, but it's probably not practical at the retail level. Although it's certainly worth investigating to find out for sure.