No I did not see the video. It's interesting that the charge is only harassment and not assault and battery if there was indeed a choking. Whether there was an injury or not is irrelevant (though it helps prove the battery). But to charge harassment is odd to say the least. If the defendant admitted grabbing the side and beard of the marcher like the cop said, why not bring assault and battery charges? At least then you don't have to prove the intention to annoy, alarm or abuse. Also, maybe I missed it but is there an explanation for why the video was suppressed? If there was no good reason the prosecution should have been able to appeal the suppression.

In the end the state had to prove beyond a reasonable doubt that the guy intended to annoy, alarm or abuse, and the judge as the finder of fact can give weight to the defendant's testimony to create reasonable doubt, even if the testimony is conflicted by the marcher and cop.

I would disagree with the author of the article that the judge is "abrogating or misunderstanding" the First Amendment. There is an exception to free speech called the "fighting words doctrine" which might apply here; although the judge didn't explicitly state it that's probably what he was talking about. But the issue here isn't a First Amendment one but a criminal one against the attacker.