I just used Seas0nPass 0.6.6 to Jailbreak my AppleTV2 and then installed the aTV Flash (black) successfully as well.


After the aTV Flash (black) Installer finished and re-started the AppleTV I quickly unplugged it and then did a "tethered boot" with Seas0nPass. 


It works like a charm.

This is interesting and seems more like the info that nito has. Do we have to keep the atv and Mac connected via the usb cable? How did you know the ATV was restarting when you installed atvflash?