Thanks for your help! I can now pass a JSON object to the flash.swf, really handy.

But a problem still exists:
http://www.depot43.ch/silverflash/flashinhalte/textfelder/textfeld1/jsonausgabe only displays with the variables from the TextFeldangabe table when I'm logged in the backend. Would there be a possibility to log in a readonly user automatically in the controller or something like that??

class TextFeldPage_Controller extends Page_Controller {


           public function jsonausgabe() {
           $data1 = DataObject::get("TextFeldangabe","TextFeldangabe.Titel='$this->URLSegment'");
           $f1 = new JSONDataFormatter();
           return $f1->convertDataObjectSet($data1);
           }

}

Thanks for your help mates!!!
JoNinjas

hey!
old post, but still I just came to the solution and maybe someone else wants to know it :)
make sure your dataobjects can be viewed for non-admins like this:

    public function canView($member = null) {
        return true;
    }