This is the man. He appeared in a later video and claimed to have thrown bricks and used a chain to strike DC Police in the legs and head. The chain is visible in photo, hanging from his neck. Calls himself 'General Major Brown', and when asked what he plans to do next, he told the interviewer: "Milwaukee, Chicago, Texas, is what I'm looking at right now."
I notified the DC Police last night, and was told that the FBI is already aware of this person and has seen the videos.