I have a 2015 SE and did the dash cam thing on mine. To pull the overhead down ON MINE (2015, Not sure of a 2012), I jammed my finger tips FIRMLY into the SIDES of the housing, forward by the sunglass holder. With an alarming amount of force, I gave a mighty pull downward and the metal tabs popped out of their sockets. The rear end just pivots out as I recall. There isn't much slack in the wiring harness so you have to pretty much fight to push the connector tabs to release the wiring plugs. I got a cheapie cigarette lighter 5vdc USB power adapter and busted it out of it's housing, removed the cigarette lighter contacts on the circuit board and replaced them with some wires. Using a VOM, the large wiring plug is where I found key-off 12v, as I recall, they were black (ground) and white (hot) and were on diagonally opposite sides of the plug. I simply cut a 1/8th" section of insulation off the wires and wrapped and soldered in the adapter wires. I got a standard USB cable that fits my dashcam, plugged it into the modified cigarette lighter gizmo, secured it and routed the cable down through the rear view mirror cable tunnel. Be sure to test functionality before you go too far. I stuffed the excess cable into the cavity above the headliner. Don't forget to INSULATE all the wiring mods and circuit board and cushion the stuff so it doesn't rattle. Pop the console back in place and you're set.
The wires I used are for the overhead lights and the dashcam begins recording when I open the door, continues to record throughout the drive and when I stop and depart the vehicle, it shuts off automatically after three minutes. I am certain no two dashcams are alike so, I cannot guarantee yours will act the same way.