I agree with Rov, I think Obama would know about this for the same reason that Rov cites - 'to save American lives torture is the only option.'
Obama has committed to 'humane treatment of all detainees wherever they may be' and he has promised to end torture but then on the other hand, state-backed assassination is regarded as illegal and immoral and yet under Obama enemy killings have increased although using drones, he actually ordered more attacks on terrorist targets in his first year in office than Bush did in two of his terms.
I mean the US military are saying that 80% of the prisoners are 'not hard terrorists'. That leaves the remainder 20%. 9 out of about 600 have come forward. If torture is the only option to extract information from them, then that is the reality of the situation of a war against terror - I think.