an open wifi can't need a password
the password is for the encryption like wep or wpa or...
1 thinking about another password then the wifi
2 trying to connect to a wifi network which rely on the person using a browser to type in a password
2 is not supported by appletv because it does not have a browser but people repport that if they set their computer to login and then have their computer share internet adhoc the appletv maybe able to connect to the computer and share it's connection