He was playing the Trayvon Martin Knockout Game. Unfortunately the white guy did not have situational awareness and was not armed so he could have taken out the feral.
How was he going to be armed? Maryland is not a Free state. Getting a carry permit is extremely difficult. The DemocRats who run Maryland approve of their subjects being disarmed and helpless. You can be pretty sure the governor and many MD legislators watch this kind of video for thrills, since they have disarmed everyone so that it can happen. .