Thanks guys, for your thoughts. For the money (around AU$100, from China) it's a nice bit of kit, with it's motion sensor activation and bluetooth and wifi connectivity to interrogate it's captured videos from your phone, also the pv recharging panel to keep it's battery alive. But in the months I've had it deployed, this is the first time I've seen anything like this.
So I won't be too hard on it. It's very good at keeping it's eye (that's this camera) on our top gate and mailbox, and video quality is good enough to identify rogues and their vehicles!
So we'll put it down to a spider activating it as it went past on it's web. It has a quite fast activation time, but obviously not quite fast enough to capture 'ol eight legs on his nightly mission!