Re: Riot gear
Sounds like a job for a smartphone app, with the phone in something like an OtterBox securely tied to you.
Start with something with a decent camera, like a Sony Experia S. You'd need to lock the exposure, or have it adjust slowly, if the camera API on Android allows that. Buffer the writes to SD via the internal storage with random file names, and/or dump the video to DropBox.
If you already using a big case, you could duct-tape a big LED bike light to it for more light, and choose one with a flashing mode for a bit of "get-your-own-back"...