This isn't the sixties and seventies, which is what you're describing. This is the 21st century, where the motto seems to be, "you looked at me funny, I'm suing you!"
Handcuff professors. Lift them up? Seriously? Can you imagine the claims of sexual assault?
Yes, seriously. You don't think the last time people protested was the 60s and 70s, do you? Remember the protests against the first Gulf war? Remember the massive, global protests against the invasion of Iraq after 9/11?
Nevermind general protests against tuition hikes (these happen all the time, some students took over a building at Columbia a year or two ago for a while, staging a sit in), against corporations, against school districts, etc., etc., etc.
Heck, remember the entertainment writer's strike.. .what, four or so years ago? People protest. A lot. There are huge protests outside G20, WTO, etc., etc. summits all over North America and the globe.
There was the million man march, there are marches on Washington for and against choice, there are protests outside clinics, outside tv networks, etc., all. The. Time.
People get arrested protesting - a lot. Always have done. Always will do. This isn't old and isn't new and that's how it works. Yes, cops warn you, then you link arms and sit down, then they say they'll arrest you if you don't move, then you go limp, then they pick you up. That's how it works in a peaceful protest, like this was. Happens all the time.