“These were created as a practical demonstration that malware can record video through the webcam without the LED indication.”
The X230 webcam sits on an internal USB bus, and its Ricoh controller accepts new firmware over that same bus. The implant writes one value at address 0x80 and the LED goes dark while the camera keeps recording. Reflashable USB webcams are a common design across laptop makers. The light you trust is a software setting.