as above, this is a “packaged hack” - a collection of hacks available individually from the good guys in a few other AppleTV hacking forums.
if you stick with “known to be good” combinations of AppleTV firmware and ATVFlash version(s), then you should be a happy camper.
however every time you want to update your AppleTV firmware (and Apple’s released two of them in the last few months, which is positively lively compared to their previous release schedule), you’ll need a corresponding update to ATVFlash to be installed onto it immediately after, or you’ll usually lose some ATVFlash functionality. reverting to a previous AppleTV firmware version after upgrading to the latest and greatest is not straight-forward.
if you insist - as i’m learning i shouldn’t - on updating to the latest AppleTV firmware before all the various hacks get updated, and then packaged into a new version of ATVFlash, then the result will be what you see here on the ATVFlash forums