I've always held contradictory positions on burning the the American Flag in protest. I've always argued that the act is free speech, protected by the first amendment. Second, that its a piss poor way to protest stuff. As a symbol, the American flag is just too big a symbol. It represents too much. Its boy scouts and school class rooms and bombs and coffins. You try and burn all that, and no one gets that you're after just the one thing.
But burning the Confederate flag is an idea I can get behind. Nothing good about a Confederate flag. It was the symbol of those who would destroy this Country in order to preserve their right to own other people. And in the modern age it is a symbol of racists. Burn that sucker.