I strongly suggest against hard wiring it.
Many systems in car are supplied with 12 volt power, which is far too much voltage for the dash cam. They typically do not accept more than 5 volts for charging and if you connect a 12 volt supply, you may either blow a fuse (best case scenario) or fry the power supply of the camera.
It also makes removal of the camera very difficult if you ever wanted to switch it to a different vehicle.
Stick to the cigarette lighter in which the camera typically plugs in, and run the wire above the head liner, windshield weather striping and passenger or driver side carpeting, and tuck it between the panel gaps of the centre storage tray.
It's a very neat and very easy install. Took me approx. 5 minutes to complete.