c# Youtube mp3 donusturucu code hatası Yardım !!!

   using System;
   using System.Collections.Generic;
   using System.ComponentModel;
   using System.Data;
   using System.Diagnostics;
   using System.Drawing;
   using System.Linq;
   using System.Net;
   using System.Text;
   using System.Windows.Forms;
  namespace youtubemp3convert
  {
     public partial class Form1 : Form
     {
        public Form1()
        {
        InitializeComponent();
    }
    bool durum = false;

    WebBrowser web = new WebBrowser();
    private void button1_Click_1(object sender, EventArgs e)
    {
           web.Document.GetElementById("youtube-url").SetAttribute("value", textBox1.Text);

    web.Document.GetElementById("submit").InvokeMember("click");

    durum = true;

              }
    string dosyadi = "";
    void Download(string link)
    {
        SaveFileDialog kaydet = new SaveFileDialog();
        kaydet.Filter = "MP3 Dosyası (*.mp3) |*.mp3";
        if (kaydet.ShowDialog() == System.Windows.Forms.DialogResult.OK)
        {
            dosyadi = kaydet.FileName;
            WebClient download = new WebClient();
            download.DownloadFileAsync(new Uri(link),dosyadi);
            download.DownloadProgressChanged += download_DownloadProgressChanged;
            download.DownloadFileCompleted += download_DownloadFileCompleted;
        }
    }

    void download_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
    {
        progressBar1.Value = e.ProgressPercentage;
    }

    void download_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)
    {
        Process.Start(dosyadi);
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        web.ScriptErrorsSuppressed = true;
        web.Navigate("http://www.youtube-mp3.org/tr");
        web.DocumentCompleted += web_DocumentCompleted;
    }
    string link = "";
    void web_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        if (durum)
        {
            HtmlElementCollection col = web.Document.GetElementsByTagName("a");
            foreach (HtmlElement el in col)
            {
                if (el.InnerText == "Download")
                {
                    link = el.GetAttribute("href");
                    Download(link);
                }
            }
            durum = false;
        }
    }

}

}

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