(Thanks to The International Libertarian)
The morality here isn't as simple as I would like. I would like to say that these poor, innocent lemonade sellers were bullied by government thugs—and they were—and leave it at that. But the sellers were on government ("public") property, and the government's armed agents were within their rights to remove trespassers, people who were engaging in non-approved activity on property they were hired to protect. And one could point out that the protestors were probably (the audio isn't clear) asked politely to desist before they were arrested. Having made their point, they could have packed up and gone home.
That said, however, I'm still on the vendors' side.
Common sense and decency on the part of the police would have dictated that they interpret the situation as an acted-out parable, much like Ezekiel symbolizing the seige of Jerusalem by cooking over a dung fire (Ez 4). What public danger would have ensued from the police saying, "Let them have their tantrum. They'll get tired eventually and leave"? Did they really think that if they didn't kill this nit the Capitol grounds would be infested with outlaw lemonade stands?
If the police would not have arrested someone carrying a sign that said, "Stop arresting lemonade and raw milk vendors," by what logic did they arrest these protestors? And now that they have arrested the lemonade protestors, will people who carry signs or put bumper stickers on their cars be next in the clink?
People not involved in the protest were buying lemonade, and no one we know of was objecting to the demonstration as disturbing the peace. (The video was obviously slanted in favor of the protest, so we cannot know for sure that no Mundanes objected to the it.) This was peaceful activity by any reasonable definition (and so not Uncle Sam's). If Mundanes had been objecting, there could have been reason for police intervention, but absent significant protest from onlookers, what reason was there for the police to intervene?
Most importantly, the protest was over the shutdown by government agents of vendors of lemonade (and, I assume, such things as raw milk) on private property. If Mundanes cannot sell lemonade and raw milk on their own property, where could this protest have taken place legally? Remember, selling lemonade is an activity that, unlike, say, beating people with baseball bats or dancing nude and having sex around a giant phallic symbol, most people in most places at most times would consider innocent. If innocent activity cannot be tolerated in public, what kind of activity can?
Judging by this video, in today's police state, peaceful activity is less to be tolerated than the abduction of peaceful people.