I am more often in support of such action, street preaching that is. Contrary to many Western Reformer of today's disagreement.
There are those who sought no personal connection with the real God saying: Where in the Bible that says we must go out to preach on the streets? There are those who felt it is wrong of God to let his disciples suffer persecution from non-believers saying: Street preaching is outdated. These are Christians who live in denial. I call them Christians, because they, I believe, are still hopeful in God's grace as they are constantly being confronted with this issue.
The video above (a preacher got his equipment confiscated by police in Springfield, Missouri) reminded me of an incident I saw in a subway station not long ago. A black preacher was shouting bunch of biblical condemnation in his preaching that irritated a chubby Muslim lady, who then raised her hand wishing to ask him a question. The preacher immediately responded "I don't have time for question" in his perhaps Jamaican accent. I felt guilty for not asking her about her question.
Obviously, that black preacher was wrong to not connect with his crowd. Many preachers on the streets, subway stations are like that. Why is that? Afraid of confrontation? Afraid of any relationship with the crowd? Why preach then? Or rather, why call it "preaching", since the real definition of preaching is not doing something an electronic speaker can also do.
To preach biblically, is to connect with the audience. None of these preachers have direct audience. This is contrary to the Bible. The reasons the Romans took Paul, or the Pharisees took Jesus, were not because of their speakers or something crazy they do to make everyone uncomfortable, but because there were audience, because they were attracting crowds. And as for John the Baptist, Elijah, Jeremiah, etc. they were persecuted by the ones they preached to DIRECTLY. This is not the case today. The preachers today preach in ignorance of the presence of either their persecutors or the bystanders.
What's my conclusion? I think they watch too many movies about preachers and they were just trying to act like them.