Megadeth frontman Dave Mustaine is sounding off on America's Commander-in-Chief.  Mustaine tells "Goldmine" magazine he thinks President Obama has been "selling off" America.  He's also unhappy with what he describes as a "plummeting" economy, and what was -- in his opinion -- a slowness to act in Libya.  But that's not all.  Dave also says he's not sold on the authenticity of the birth certificate that the President recently showed to his fellow Americans.  Mustaine claims he once used something similar to "buy booze."  He adds that they used to sell certificates like that "in the back of 'Creem' magazine for three dollars."