This is the UB4 position. Both parents citizenship is a requirement, place of birth is incidental. It is no the same as the theory based on the 18th century book cited above.
Which is it?
sorry should say NB4 not UB4. Typo.
Which 18th century book, Blackstone or the French guy's?? But really It's both, in that the English version, having both parents be subjects as one criteria, as did the French. The English just added in place of birth as second alternate criteria, so that children of foreigners born in the realm were also "Natural born" subjects. (Both versions also went with the father's nationality if their was a split).
In Obama's case I suspect it won't matter. If he was born outside the US, He doesn't meet either criteria, nor the statutory criteria for being citizen at birth (whether or not that makes one natural born). What else would justify not revealing the actual long form BC, or even having a certified paper copy of the short form sent to one of the courts involved,