JPP
Active Member
With the blackvue 650GW the rear camera gets one cable which carries both power to it and the signal from it. So you don't need to find power in the back of the car.
In the front the mic cover may (depends on your car) have a permanent 12V supply available. Otherwise you can solve it several ways, I used a hack on the ODBII connector near the drivers left foot to get permanent 12V so I could catch things while parked like what the OP said (fortunately never happened to me as I think i'd have a heart attack).
Please also see this thread:
DIY Dashcam (BlackVue 550 fronrear) - constant power source from dash
with additional photos and notes.