I'm trying to educate myself on mobile DVR's to record 4 wheeling from built in cameras that run to Video Head Units. I know there are guys out there recording their action and wondered if anyone has some input on which are good? I've heard there are some that plug into the USB connectors? 
Or suggestions on where to get educated? I've googled the piss out of this and I'm not finding what I'm looking for.
Thanks.

Or suggestions on where to get educated? I've googled the piss out of this and I'm not finding what I'm looking for.
Thanks.