Best way to block Hotspot Shield advertisements

This is simplest and fastest, same for most browsers.

All you need to do is to put this in a text file, eg, c:\hotspot.pac

function FindProxyForURL(url, host) {
  if (shExpMatch(url,"*anchorfree*"))
     return "PROXY 127.0.0.1:12768";
        /*any unused port will block ad*/
  else
     return "DIRECT";
}

Most browsers support automatic proxy configuration. In Firefox its at Tools>Options>Network>Settings>Automatic proxy configuration URL

You enter the filename:
flile://c:/hotspot.pac

You can also do fancy things such as ensure that Hotspot Shield is on before allowing internet access, to protect your IP against Hotspot, which may disconnects you at anytime without notice. That's for another day.