query vars in url work but not in ajax call

Question

That’s not the right way to specify data.

When you’re using jQuery AJAX, you specify data as an array or an object when passing it in to the method. In your question, it seems like

'filters_get' === '?actor=x&'

Instead, you should do the following:

filters_get = {
    'actor': 'x'
};

$.ajax({
    url: templatePath + "getmovies.php",
    type: "GET",
    data: filters_get,
    cache: false,
    success: function (data){
        console.dir(data);
    }
});

jQuery will internally parse the URL to automatically create the query string args for you. From the jQuery documentation, the data parameter is:

Data to be sent to the server. It is converted to a query string, if not already a string. It’s appended to the url for GET-requests.

Your format shouldn’t have the ? in it, because that will break the string. But it’s easier to deal with the encoding if you just pass an object (associative array) instead.