There are a couple things to note about this Jailbreak.
It is a tethered Jailbreak, meaning you will have to reboot it while plugged into your compter everytime.
EDIT*** – NOW SUPPORTS UNTETHERED JAILBREAK AND DOESN’T NEED TO BE BOOTED!!!
2) This only works on version 4.2.1
3) If you look under settings on your aTV it will say version 4.1.1. This is the same thing as 4.2.1
Check out the video below for a simple how to video.