You cannot download it as it is a standard plugin included in the Zenphoto package (which is noted on the page). To add further: The flags are actually an option of the dynamic_locale plugin. The flags itself are a component of the translation files within /zp-core/locale. As said you will need to do some changes as you of course should not change these (they will be overwritten on updates anyway).
I am experiencing the same thing too, where I cannot get the flags to disappear. I am trying to get a pulldown menu in its place as was before the flag selector feature was introduced.
One should use printLanguageSelector(); in the theme where it ought to appear, and uncheck "use flags" in the dynamic locale option, right?
Sorry, I had seen that and made a syntax error. thanks.
For the record, this is how to place the function in a theme: printLanguageSelector(false);
Or printLanguageSelector(); and disable it in the admin.
I had another variable in the parenthesis, something from the past that is not relevant, and that made it so that only the flags would show no matter what the setting was.