Q: How does the Xbox One control other devices?
A: When configuring the Xbox One, you tell it the make of your TV, AVR, and set-top/cable box. This allows the Xbox One to then control those other devices, for example automatically turn them on and off with the Xbox One and also change channels.
The way it actually works is the remote control is enabled through the Kinect, which acts like an IR Blaster. You might wonder how this works since your TV or other peripherals might not have line of sight to the front of the Kinect and might even be behind the Kinect. The IR Blaster in the Kinect actually leverages the objects in the room such as walls and bounces the IR signals off walls and objects to control the devices configured for the Xbox One. Pretty cool!