Here's the main thing you guys have to remember: Military members are American citizens just like you are. They have the same worries, fears, and problems that every other American citizen has. If there came a point in time where civil unrest was at an extreme level, and for some insane reason our constitution was shattered and the military tried taking over for martial law, who would be those military members? They are American citizens, who probably would have the same views as the rest of the public. Do you honestly think, if unrest was THAT bad, that they would go along with some dictatorship government and allow the martial law? The generals, admirals, and other high ranking officers are also citizens, and I doubt they would agree to such a command.
Most military members are there for a patriotic duty to protect the lives and lively-hood of America and its people. The military isn't there to hurt its own public. This isn't like Julius Caesar marching into Rome with his legions, and replacing the Republic with an Emperor/Dictatorship. We are in the year 2012 AD, not in the year 800 BC. Also, until the country becomes fascist or the bolshevik revolution occurs in the USA, I don't see ourselves allowing the next Nazi or Communist state either. You are definitely more worried than you should be.