Animal rights group Direct Action Everywhere provided WIRED the first hidden camera video from inside a CO2 gas chamber in a US slaughterhouse. To get it, one activist snuck into the plant (with a fake uniform and badge) climbed into the underground chamber, and planted tiny infrared cams.
The DIY cameras she planted, which connect via a Wifi to a hidden phone to transmit the footage, include an infrared LED, a microphone, and enough battery for days of recording. The whole setup is smaller than a credit card.
