For $650, I just purchased a consumer-level CCTV (writes locally, on a loop) which can auto-detect all humans, vehicles, and pets — creating montages of visitors (for later review). This is entirely offline, eight camera, just over two weeks retention at 12MP (configurable to months with dual SATA slots and video setting changes).

What cloud recording is capable of determining... is absolutely limitless. I think this is what makes Flock so scary / "different."