I'm an American, and even after serving my government's questionable goals in a relatively unpopular middle east campaign I'm still a patriot. I'm no fool, I'm not a blind patriot, but I do have some fairly firm principles. One of those principles is returning service for service rendered.
My nation has sheltered me in times of conflict and provided for me in times of poverty. Unlike many Americans who dislike their nation and its government so much, I have been to other countries, I have seen that we enjoy a standard of living not available to others. As a young man I felt it was my duty to return the freedom my nation offered by volunteering to help protect that feedom.
I no longer serve my nation in the military. That part of my life is over, but I still stand to be counted as a patriot. Having said that, the only thing that upsets me more than seeing someone burning an American flag in protest, is listening to people talk about how the practice should be banned.
The right to protest is one of the foundations of our federal government, and although I believe it is wrong, the right to burn flags in protest should be protected. To put a finer point on it; I believe flag burning in protest is the grossest display of the ungrateful and the ignorant, but, I would fight to the death to protect your right to do so.
Update: Albert Herring brought up the extremely good point that my wu was delinquent in not mentioning. If you are not a resident or member of the nation, then burning the flag in protest assumes an entirely different emotive response. An argument could certainly be made for resident aliens being ungrateful, but non-residents burning the flag of nation A while actually standing in nation B is quite different. That's just insulting, as I'm sure it is meant to be.