The download page now has the following

Error: Please do not destroy our service. It is funded by Premium accounts, so please be fair and do not hide the Premium features and payment options. If we have to close the service, no one will benefit. Thank you.

File Download | Free User

I tested the following. Although it is not elegant, it seems to handle the new message

function isError() {
var err = "";
if (inhaltbox.getElementsByTagName("h1").length > 0) {
err = inhaltbox.getElementsByTagName("h1")[0].innerHTML; // content of the first H1 element in "inhaltbox" div
if (err.indexOf("Error: Please do not destroy our service") > -1) {
return false;
}
else if (err.indexOf("Error") > -1) {
return true;
}
else {
return true;
}
}
return false;
}

oops forgot to tag the code

Error: Please do not destroy our service. It is funded by Premium accounts, so please be fair and do not hide the Premium features and payment options. If we have to close the service, no one will benefit. Thank you.
File Download | Free User

and

	function isError() {
		var err = "";
		if (inhaltbox.getElementsByTagName("h1").length > 0) {
			err = inhaltbox.getElementsByTagName("h1")[0].innerHTML; // content of the first H1 element in "inhaltbox" div
			if (err.indexOf("Error: Please do not destroy our service") > -1) {
			  return false;
			}
      else if (err.indexOf("Error") > -1) {
				return true;
			}
			else {
        return true;
      }
		}
		return false;
	}