Though the author will, no doubt, know what they is trying to and how they is trying to do it... their statement is merely an overview.
Where as I get made fun of for supplying copious amounts of detail *sigh*
Though 'get power' does imply sourcing the power, it might also mean 'get power' by running extra cabling (e.g. cable for camera) - hard to know without further details.
Just taking a guess here (not having a GD3 to inspect)...
They mentioned 'in car camera' (I am assuming either for pointing out the rear - i.e. rear crash cam; or cabin camera - passenger surveillance and/or crash cam footage). In either instance the easiest place to mount it would probably be at the top of the rear windscreen glass and you could hide the cables under trim, run through existing seals, etc.. So I am assuming they is either
a) hoping to connect to a 12V source in the boot door - (I think the motor, or control, for the parking camera deployment mechanism has 12V with IGN on) - such as if the camera is a complete 'dash cam' or is otherwise wireless (power would still be needed - but would assume to be sourced from 12V) 2nd camera; or
b) wishing, for a wired 2nd camera to a dash cam (such cameras usually run on much less than 12v), to run the cable (inc. power) to the camera via. the existing grommets/seals, flexible conduits, etc. - e.g. not compromise factory seals, there appears to be only one to supply everything in the boot door (plus washer hose).
Looking at a photo of a GD3 hatch boot door open where I can only see part of where the cables go into it - something that
cruiserfied might be able to answer is how does one access at the top of boot the cables going into it? Internal trim piece removal? Or via spoiler removal? I would have thought internal trim - as via. spoiler would require a big enough hole for access and an external seal (potential failure point) to seal it.
Like
cruiserfied I would wonder about spoiler removal to 'get power' (unless it is the way to access all incoming cabling) for a camera - unless the camera was going to be mounted on the outside of the car (but that contravenes 'in car camera' statement). Many remote/2nd camera's for a dash cam rely on the dash unit to supply it with operating power at the right voltage (typ. 3.3v to 5v) for the camera (for a number of reasons - reduced component count, wiring, etc.. being a couple) - so the above mentioned 12V source would unlikely be useful in such a case; and the actual park/rear camera electronics (camera and deployment mechanism appear to be electrically separate) run on 6.6V (from memory) and is supplied only when it is activated (e.g. reverse)... so wouldn't be useful for constant supply.
