Is the "password:" line really blank, or did you just remove the password?
It looks like that's actually the line that's giving it trouble.
Make sure there are no tabs where there should be spaces, and that there's
no whitespace at the end of the line; I don't know if either is *supposed*
to matter to YAML, but Ruby and tabs can do weird things on Windows.
Try switching the order of the password: and username: lines, and see if
the error now lists username instead of host. And (assuming the passwords
are the same or really blank) try swapping two of the password: lines, or
retyping the line from scratch. Look at the file in a hex editor and see
if there's anything weird with line endings (CRLF vs LF).