Sentry consumes around 200W on Intel Atom and camera based detection enabled. I'd say it's a total overkill. It even heats up the display pretty good when it's relatively chilly outside.
Even so, you shouldn't be waking all 24 cores, the GPU, etc. just to record video. Let the cameras DMA into their buffers and wake up a single core when the buffers hit a high water line. The core only needs to be awake long enough to queue up the writes to storage and then it can go back to sleep.