We do not see the beginning of the conversation - the video starts after they had already began talking. Therefore, nobody knows who instigated it. Although by the context of the conversation, and the fact the elderly man expresses that, "you asked me!?" phrased as a question - suggests that the black man had brought up the "shoe shining" to begin with.
This is all irrelevant however, because as shown by video evidence, the elderly man attempts to reduce hostility by moving away from the black man to avoid further confrontation. What happens? Along with egging on by the black female, the black male pursues the elderly man with violence. This heavily implies that the black man was attempting to start the fight to begin with - if the elderly man really tried to antagonize the guy, he wouldn't have moved away shortly after starting it. It's simple logic.
