Before installing aTV Flash (black) the Apple TV will need to be 'jailbroken' - this allows 3rd party software to be installed.
What is jailbreaking?
Jailbreaking allows 3rd party (non-Apple) software to be installed on your Apple TV.
Is jailbreaking legal?
Yes! A recent ruling from the US Copyright office has officially declared jailbreaking 100% legal.
Will all my normal Apple TV features still work?
Yes, all normal Apple TV features (iTunes media playback, rentals, photos, Netflx, AirPlay, etc...) will remain intact and unchanged.
What about my warranty?
If needed, the Apple TV can be easily restored to it's factory state through iTunes - removing any and all 3rd party software (including all traces of jailbreaking).
Ok great. How do I jailbreak my Apple TV?
More info on jailbreaking with the free Seas0nPass app can be found here.