How, exactly, do we know that the protestors are not starting the violence? How do we know what, if anything is going on? Where's the proof?
The proof is all over Youtube. Everything happening at the Occupy camps as well as the protests they organize is streamed live where thousands of people are keeping one eye on the video and one finger poised over the rewind button. Links to footage are tweeted and retweeted within seconds of their hitting the Net. Videos are not only being watched but mirrored to be put back up later in the event of legal shenanagains (the so-called Streisand effect). In the event that something does go down (such as the hit-and-run I mentioned) analysis and extra evidence is compiled and released (local mirror of the license plate and driver) to tell the other side fo the story. The one you're not getting on the evening news.
Sousveillance is how we know.
Depending on how you translate the term, it can mean either "surveillance from below" (i.e., when the watcher isn't part of the upper echelons of the society in question), or surveillance by being a participant in something. In practice, sousveillance is carried out by someone using wearable computing and sensor technology to observe, record, and usually transmit what happens around them to a location where it can be viewed by others. It is thought by many that both the term and the practice originated from the work of Professor Steven Mann of the University of Toronto (by way of MIT and McMaster University), in which he began research into not only wearable computer technology in the early 1980's but also personal surveillance equipment as a reaction to the proliferation of security cameras. It should be noted that Professor Mann is a staunch advocate of privacy and a critic of surveillance of people "just because." Until very recently, the only practical way of carrying out sousveillance or inverse surveillance was to build your own gargoyle rig and cause a stir whenever you went out (as Professor Mann was known to go when walking into stores).
Nowadays, all you need is a fairly recent smartphone (Android or iProduct, it doesn't matter which), a commodity microcamera like this or this, or even these hipster glasses (which you can probably get corrective lenses for), a few gigs of storage for your phone or other device, and an account or three on your favorite streaming video site like Youtube, Livestream, Qik (here's mine). Of course, your mobile will need data access of some kind, usually a data plan from a cellular carrier but local wi-fi will work in a pinch to upload audio and video. You will also need one of the many free apps out there that allow you to stream live and direct (or at least after the fact when you get someplace with a clear signal), which you can usually download for your mobile right from the website. There are also third party applications out there like Openwatch that are specifically designed for sousveillance efforts.
(Disclaimer: I have put no Amazon referral links in this article. If you decide to buy any of this kit I won't see a penny of compensation, but it will give me warm and fuzzy feeling if you tell me.)
That's it. A little cash outlay, a few minutes reading the documentation (you DO read the docs, right?) while you charge the power cells and install some software, and you're all set to take part in World Sousveillance Day. Or your local Occupy protest. You may not be able to save any lives by donning an earplug-sized sensor module or two but you may help bring someone to justice. This is how the whole world found out what happened in Oakland, California when riot police stormed the protestors and a former US Marine was shot in the face by police.
The best advice I can give you if you decide to become the eyes and ears of thousands is this: don't get caught. In very recent memory (2010 and 2011 to be precise) a number of people have done just this and as a result at least three states (and probably more by now) have made it illegal to record police officers on duty for any reason. Even if you're standing on your front porch and they're across the street. Especially if you're trying to file a complaint and they have every reason to stonewall you. Even in situations where there is no expectation of privacy at all (such as standing on the sidewalk), what is most often done is that the police will try to charge you under anti-wiretapping laws even though you're not actually tapping any phones. When charges are filed and cuffs come out, you're in the soup so get a lawyer.
Charles Fort was correct for a short time only when he wrote the famous words "I think we're property." Our warranties are up and now we're taking back what's ours: this world. Keep your eyes open, your link low-latency, and your boots on.