The main thing I want to stress is to stay safe.
Directly aiming a video or cell phone camcorder in a police officers face is not safe. That same officer trying to take your camcorder or mobile phone and aiming a gun?This is a quick and dirty round-up of resources folks can use or ramp up to speed concerning recording actual events.
Give the camcorder up. Otherwise ask why or refuse with the understanding you might go to jail.
Climbing unsteady surfaces to get the video is not safe.
Getting encased in a mob action, so not safe.
Electronic Freedom Foundation page on Bloggers' Rights and the Legal Guide to Bloggers
YouTube has the Project Report channel where folks can upload news and public interest videos. In addition there is a section on the channel page where you can watch videos about how to do it better.
Daily Kos has a list of resources for those people that practice citizen journalism as a normal part of their blogging experiences. It is a long list but there might be something that can lead to a helpful web site or blog.