Program: 20728
Project: 20728
Buggy source:
@Override public void handlePremium(DownloadLink downloadLink,Account account) throws Exception {
  br.setFollowRedirects(true);
  String linkurl=null;
  requestFileInformation(downloadLink);
  br.setDebug(true);
  Form profidown=br.getFormBySubmitvalue("String_Node_Str");
  if (profidown == null)   br.getFormbyProperty("String_Node_Str",Encoding.urlEncode("String_Node_Str"));
  if (profidown == null)   throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
  String id=br.getRegex("String_Node_Str").getMatch(0);
  if (id == null)   throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
  login(account);
  checkPremiumIP();
  br.getPage("String_Node_Str");
  String[] links=br.getRegex("String_Node_Str").getColumn(0);
  for (  String link : links) {
    if (link.contains("String_Node_Str" + id)) {
      linkurl=link;
      break;
    }
  }
  if (linkurl == null) {
    requestFileInformation(downloadLink);
    profidown=br.getFormBySubmitvalue("String_Node_Str");
    if (profidown == null)     br.getFormbyProperty("String_Node_Str",Encoding.urlEncode("String_Node_Str"));
    if (profidown == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
    id=br.getRegex("String_Node_Str").getMatch(0);
    if (id == null)     throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
    br.submitForm(profidown);
    Form login=br.getForm(0);
    login.put("String_Node_Str",Encoding.urlEncode(account.getUser()));
    login.put("String_Node_Str",Encoding.urlEncode(account.getPass()));
    login.put("String_Node_Str","String_Node_Str");
    br.submitForm(login);
    links=br.getRegex("String_Node_Str").getColumn(0);
    for (    String link : links) {
      if (link.contains("String_Node_Str" + id + "String_Node_Str")) {
        linkurl=link;
        break;
      }
      if (link.contains("String_Node_Str" + id + "String_Node_Str")) {
        linkurl=null;
        br.setFollowRedirects(false);
        br.getPage(link);
        linkurl=br.getRedirectLocation();
        if (linkurl == null)         linkurl=link;
        br.setFollowRedirects(true);
        break;
      }
    }
  }
  if (linkurl == null)   throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
  dl=jd.plugins.BrowserAdapter.openDownload(br,downloadLink,linkurl,true,0);
  URLConnectionAdapter con=dl.getConnection();
  if (!con.isOK()) {
    con.disconnect();
    throw new PluginException(LinkStatus.ERROR_PREMIUM);
  }
  dl.startDownload();
  if (downloadLink.getLinkStatus().hasStatus(LinkStatus.FINISHED)) {
    String kod=new Regex(linkurl,"String_Node_Str").getMatch(0);
    if (kod != null)     br.postPage("String_Node_Str","String_Node_Str" + kod);
  }
}

Fixed version (ground truth):
@Override public void handlePremium(DownloadLink downloadLink,Account account) throws Exception {
  br.setFollowRedirects(true);
  requestFileInformation(downloadLink);
  login(account);
  checkPremiumIP();
  br.getPage(downloadLink.getDownloadURL());
  String dllink=br.getRegex("String_Node_Str").getMatch(0);
  if (dllink == null)   dllink=br.getRegex("String_Node_Str").getMatch(0);
  if (dllink == null) {
    logger.warning("String_Node_Str");
    throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
  }
  dl=jd.plugins.BrowserAdapter.openDownload(br,downloadLink,dllink,true,1);
  URLConnectionAdapter con=dl.getConnection();
  if (!con.isOK()) {
    con.disconnect();
    throw new PluginException(LinkStatus.ERROR_PREMIUM);
  }
  dl.startDownload();
}