At least based on this article "Know Your Rights: Photographers" (http://www.aclu.org/free-speech/know-your-rights-photographe...) what he is doing is perfectly legal: video-taping while standing on public property. On private property it is not ok and you have to leave when asked, which he does.
The situation only gets tricky because of the audio, and in this case it matters what state you're in. Still, it seems like the legality hinges on "reasonable expectation of privacy", which someone casually sitting at a Starbucks probably does not, or at least should not have. Also, in all cases the subject is clearly aware of being recorded.
On the other hand, in one of the clips two guys call the police and he runs away trying to avoid confrontation. That seems odd.