The guy sounds like a moron.
I tested cex.io for a week with 1.5 btc and left with 2.2.
Pretty decent return, just didn't have the time to invest, even if you just bought GHs, it's normally cheaper than buying the hardware and you get the same results... plus you can resell it easily.. (While everyone is waiting for things to ship and then the hardware you have becoming useless.)
Guy sounds like a moron?

?
You earn 0.7btc in one week with 1.5btc worth of hashing power from cex.io?

no no no no no, you earn more then that because you sell you hash power for less than you pay for!
LOL
Do you really thing that there is so dumb people to believe that???
This was funnies shit I heard since ButterflyLabs.