I’ve been getting this error for a little while now. It either started when I reformatted my OSX Tiger system, or did a factory reset on the Apple TV.
I have gone into Terminal and got rid of the cached keys, but I still get the message.
I use Cyberduck (3.4.2 (5902) for FTP.
The host is currently unknown to the system. The host key fingerprint is xxxxxxxxxxxxxxxxxxxxxxx
Clicking on Always does not change anything.