Mac: How to jailbreak AppleTV 2G (black) 4.2.1, with video

Greetings,

I successfully installed aTV Flash on my new AppleTV 2G running 4.2.1 - I followed a great video tutorial on YouTube to jailbreak it. It's a tethered jailbreak still, and the process is not for the faint of heart (proceed only if you know how to use Mac Terminal). But I thought I'd share in case anyone is impatient like me.

YouTube video: http://www.youtube.com/watch?v=4EWKr7Ww_c0