Program: 21128
Project: 21128
Buggy source:
public void handleFree(DownloadLink downloadLink) throws Exception {
  boolean do_download=false;
  getFileInformation(downloadLink);
  br.setFollowRedirects(true);
  String watchAd=br.getRegex("String_Node_Str").getMatch(0);
  if (watchAd != null) {
    downloadLink.getLinkStatus().setStatusText(JDLocale.L("String_Node_Str","String_Node_Str"));
    watchAd="String_Node_Str".concat(watchAd);
    br.getPage(watchAd);
    watchAd=br.getRegex("String_Node_Str").getMatch(0);
    if (watchAd == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    br.getPage(watchAd);
    watchAd=br.getRegex("String_Node_Str").getMatch(0);
    if (watchAd == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    br.getPage(watchAd);
    String ticketTimeS=br.getRegex("String_Node_Str").getMatch(0);
    if (ticketTimeS == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    int ticketTime=Integer.parseInt(ticketTimeS) * 1000;
    this.sleep(ticketTime,downloadLink);
    br.getPage(watchAd);
  }
  for (int retry=1; retry <= 5; retry++) {
    Form captchaForm=br.getFormbyProperty("String_Node_Str","String_Node_Str");
    String captchaurl=br.getRegex("String_Node_Str").getMatch(0);
    String tag=br.getRegex("String_Node_Str").getMatch(0);
    String secret=br.getRegex("String_Node_Str").getMatch(0).substring(2);
    if (captchaForm == null || captchaurl == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    if (tag != null && secret != null) {
      captchaForm.put("String_Node_Str",tag);
      InputField nv=new InputField(secret,"String_Node_Str");
      captchaForm.addInputField(nv);
    }
 else     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    captchaForm.setAction(br.getURL());
    URLConnectionAdapter con=br.openGetConnection(captchaurl);
    File file=this.getLocalCaptchaFile(this);
    Browser.download(file,con);
    String captchaCode=getCaptchaCode(file,downloadLink);
    captchaForm.put("String_Node_Str",captchaCode);
    br.submitForm(captchaForm);
    String directLink=br.getRegex("String_Node_Str").getMatch(0);
    if (directLink != null) {
      dl=br.openDownload(downloadLink,directLink,true,-2);
      do_download=true;
      break;
    }
  }
  if (!do_download) {
    throw new PluginException(LinkStatus.ERROR_CAPTCHA);
  }
 else   dl.startDownload();
}

Fixed version (ground truth):
public void handleFree(DownloadLink downloadLink) throws Exception {
  boolean do_download=false;
  getFileInformation(downloadLink);
  br.setFollowRedirects(true);
  String watchAd=br.getRegex("String_Node_Str").getMatch(0);
  if (watchAd != null) {
    downloadLink.getLinkStatus().setStatusText(JDLocale.L("String_Node_Str","String_Node_Str"));
    watchAd="String_Node_Str".concat(watchAd);
    br.getPage(watchAd);
    watchAd=br.getRegex("String_Node_Str").getMatch(0);
    if (watchAd == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    br.getPage(watchAd);
    watchAd=br.getRegex("String_Node_Str").getMatch(0);
    if (watchAd == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    br.getPage(watchAd);
    String ticketTimeS=br.getRegex("String_Node_Str").getMatch(0);
    if (ticketTimeS == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    int ticketTime=Integer.parseInt(ticketTimeS) * 1000;
    this.sleep(ticketTime,downloadLink);
    br.getPage(watchAd);
  }
  for (int retry=1; retry <= 5; retry++) {
    Form captchaForm=br.getFormbyProperty("String_Node_Str","String_Node_Str");
    String captchaurl=br.getRegex("String_Node_Str").getMatch(0);
    String tag=br.getRegex("String_Node_Str").getMatch(0);
    String secret=br.getRegex("String_Node_Str").getMatch(0).substring(2);
    if (captchaForm == null || captchaurl == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    if (tag != null && secret != null) {
      captchaForm.put("String_Node_Str",tag);
      InputField nv=new InputField(secret,"String_Node_Str");
      captchaForm.addInputField(nv);
    }
 else     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFEKT);
    captchaForm.setAction(br.getURL());
    URLConnectionAdapter con=br.openGetConnection(captchaurl);
    File file=this.getLocalCaptchaFile(this);
    Browser.download(file,con);
    String captchaCode=getCaptchaCode(file,downloadLink);
    captchaForm.put("String_Node_Str",captchaCode);
    br.submitForm(captchaForm);
    String directLink=br.getRegex("String_Node_Str").getMatch(0);
    if (directLink != null) {
      dl=br.openDownload(downloadLink,directLink,true,-2);
      do_download=true;
      break;
    }
  }
  if (!do_download) {
    throw new PluginException(LinkStatus.ERROR_FATAL,JDLocale.L("String_Node_Str","String_Node_Str"));
  }
 else   dl.startDownload();
}