What do you think of this: I found a pre-northern island UK flag and burnt it on independence day once.
What do you have against pre-UK flags?
It did not represent me and my current views, and was therefore disrespectful of my culture.
You may have different views from those of other countries, but burning their flag is disrespectful. Respect other countries as you would want to be respected.
Maybe, but what about my First Amendment right to free speech?
Well, if you're making a political statement, I guess you have a point. If you're were just trying to annoy  someone that would be different. Political speech, if you don't agree with it, can be unpleasant and abrasive.