I've received a review copy of this from the OP and here is my review of it:

It is a legal method that has some risks in it.  The earnings generated depend on availability, which I cannot verify due to the fact that I am in Canada.  Although it is not guaranteed earnings, its risks are low if you are able to calculate and strategize, and with a bit of luck, you can profit.  
I haven't tested this method myself but it is legit - guaranteed earnings, no.  Guaranteed earnings if the conditions are met: yes.  The earnings are conditional by some things that you can't really control.

In conclusion, it's a great method if the conditions are met, I can't say more than that.