C# YouTube Audio / Video downloader [VEVO videos, audio: MP3, AAC, Ogg, etc.]

Code
using System;

using System.Collections.Generic;

using System.Linq;

using System.Net;

using System.Text;

using System.Threading.Tasks;

using System.Web;



namespace YtDownloader

{

    public class YoutubeVideoDownloader

    {

  public event EventHandler<DownloadProgressChangedEventArgs> DownloadProgressChanged;



  /// <summary>

  /// Return information about a video

  /// </summary>

  /// <param name="vid">Video id</param>

  /// <returns>Tuple where the first item is video title and second item is a list of tuples of form: itag, resolution/quality string, video download URL</returns>

  public async Task<Tuple<string, List<Tuple<int, string, string>>>> DownloadVideoInfo(string vid)

  {

    var webClient = new WebClient();



    webClient.Headers.Add("Referer: http://www.youtube.com/");

    await

    webClient.DownloadStringTaskAsync(

    string.Format("http://www.youtube.com/watch?v={0}&gl=US&hl=en&has_verified=1", vid));

    string videoInfo =

    await

    webClient.DownloadStringTaskAsync(

    string.Format(

    "http://www.youtube.com/get_video_info?&video_id={0}&el=vevo&ps=default&eurl=&gl=US&hl=en", vid));



    var parsedVideoInfo = HttpUtility.ParseQueryString(videoInfo);

    var fmtMap = HttpUtility.ParseQueryString(parsedVideoInfo["url_encoded_fmt_stream_map"]);

    var fmtSplitted = parsedVideoInfo["url_encoded_fmt_stream_map"].Split(',');



    var results = new List<Tuple<int, string, string>>();



    if (fmtSplitted.Length > 0 && HttpUtility.ParseQueryString(fmtSplitted[0]).AllKeys.Contains("sig"))

    {

    // sigs & urls in strings

    foreach (var str in fmtSplitted)

    {

    var parsedStr = HttpUtility.ParseQueryString(str);



    results.Add(

    new Tuple<int, string, string>(

    int.Parse(parsedStr["itag"]), GetDimension(int.Parse(parsedStr["itag"])),

    parsedStr["url"] + "&signature=" + parsedStr["sig"]));

    }



    }

    else

    {

    throw new Exception("Unable to parse");

    }



    return new Tuple<string, List<Tuple<int, string, string>>>(parsedVideoInfo["title"], results);

  }



  public async Task DownloadVideoAsync(string vid, string outputFile, string url, int itag)

  {

    var webClient = new WebClient();

    webClient.DownloadProgressChanged += (s, ea) =>

  {

  if (DownloadProgressChanged != null)

  DownloadProgressChanged(s, ea);

  };



    webClient.Headers.Add("Referer: http://www.youtube.com/");

    await webClient.DownloadFileTaskAsync(url, outputFile);

  }



  public string GetDimension(int itag)

  {

    switch (itag)

    {

    case 5:

    return "FLV/240p - MP3/64kbps";

    case 6:

    return "FLV/270p - MP3/64kbps";

    case 13:

    return "3GP/- - AAC";

    case 17:

    return "3GP/144p - AAC/24kbps";

    case 18:

    return "MP4/270p - AAC/96kbps";

    case 22:

    return "MP4/720p - AAC/192kbps";

    case 34:

    return "FLV/360p - AAC/128kbps";

    case 35:

    return "FLV/480p - AAC/128kbps";

    case 36:

    return "3GP/240p - AAC/38kbps";

    case 37:

    return "MP4/1080p - AAC/192kbps";

    case 38:

    return "MP4/3072p - AAC/192kbps";

    case 43:

    return "WebM/360p - Vorbis/128kbps";

    case 44:

    return "WebM/480p - Vorbis/128kbps";

    case 45:

    return "WebM/720p - Vorbis/192kbps";

    case 46:

    return "WebM/1080p - Vorbis/192kbps";

    case 82:

    return "MP4/360p - AAC/96kbps";

    case 83:

    return "MP4/240p - AAC/96kbps";

    case 84:

    return "MP4/720p - AAC/152kbps";

    case 85:

    return "MP4/520p - AAC/152kbps";

    case 100:

    return "WebM/360p - Vorbis/128kbps";

    case 101:

    return "WebM/360p - Vorbis/192kbps";

    case 102:

    return "WebM/720p - Vorbis/192kbps";

    case 120:

    return "FLV/720p - AAC/128kbps";

    }

    return "Unknown (" + itag + ")";

  }

    }

}