I see nothing in this definition that relates to anything but the spoken or gestured word. So no, I do not think it should be legal to burn our nations flag.
speech
–noun 1. the faculty or power of speaking; oral communication; ability to express one's thoughts and emotions by speech sounds and gesture: Losing her speech made her feel isolated from humanity.
2. the act of speaking: He expresses himself better in speech than in writing.
3. something that is spoken; an utterance, remark, or declaration: We waited for some speech that would indicate her true feelings.
4. a form of communication in spoken language, made by a speaker before an audience for a given purpose: a fiery speech.
5. any single utterance of an actor in the course of a play, motion picture, etc.
6. the form of utterance characteristic of a particular people or region; a language or dialect.
7. manner of speaking, as of a person: Your slovenly speech is holding back your career.
8. a field of study devoted to the theory and practice of oral communication.
Felt like I probably needed to go ahead and add this definition in also.
ges·ture
–noun 1. a movement or position of the hand, arm, body, head, or face that is expressive of an idea, opinion, emotion, etc.: the gestures of an orator; a threatening gesture.
2. the use of such movements to express thought, emotion, etc.
3. any action, courtesy, communication, etc., intended for effect or as a formality; considered expression; demonstration: a gesture of friendship.
–verb (used without object) 4. to make or use a gesture or gestures.
–verb (used with object) 5. to express by a gesture or gestures.