Comcast's terms of service specify that they'll use their WiFi Motion service to tell the police or any other third party about your movements at home, should you turn it on. [via Hacker News]
Subject to applicable law, Comcast may disclose information generated by your WiFi Motion to third parties without further notice to you in connection with any law enforcement investigation or proceeding, any dispute to which Comcast is a party, or pursuant to a court order or subpoena.
WiFi Motion is a feature that uses Comcast routers to detect motion in your home—a place in which you are often present and typically moving around in.
Pet sensitivity
If you'd like to prevent your pet's movement from causing motion notifications, you can exclude pet motion in your WiFi Motion settings by turning on the Exclude Small Pets feature.
Comcast insists, in bold type, that WiFi Motion is "not a home security service." As that would be the most obvious use of it for the resident, they're making clear it's really for the entirely non-proverbial third parties specified by the terms of service. The good news is that it's off by default—and you should not turn it on.
WiFi 7 (IEEE 802.11be) formalizes these sensing capabilities, to a resolution permitting gesture recognition.
