how to capture a thumbnail from a .flv video

Hi all,

I am creating a website similar to youtube, so after uploading videos (that will be in .flv format), a thumbnail has to be captured from that corresponding video.. here i am designing my page using asp.net & c#...

I have got  some code from the net, but its working only videos of size 2-3Mb....

any one can help me to work my code for large sized files..

here's my code..

my code in default page(default.aspx.cs)..
its in page load method....

  protected void Page_Load(object sender, EventArgs e)
        {
            Class1.GrabSingle_Thumb();
        }

code of my class file(class1.cs)...

using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Text;
using All4DotNet;


namespace LiveStreaming
{
    public class Class1
    {
        public static void GrabSingle_Thumb()
        {
            //Declare object of class MediaManagerPro
            MediaManagerPro oMediaManagerPro = new MediaManagerPro();

            //Get the rooth path
            string strRootPath = HttpContext.Current.Server.MapPath(HttpContext.Current.Request.ApplicationPath);

            //set the directory path info for ffmpeg file
            oMediaManagerPro.FFMPEG_Path = HttpContext.Current.Server.MapPath("~\\ffmpeg\\ffmpeg.exe");

            //Set source file info
            oMediaManagerPro.SourceFile_Path = strRootPath + "Videos";
            oMediaManagerPro.SourceFile_Name = "HelloWorld.flv";

            //set output file info
            oMediaManagerPro.OutputFile_Path = strRootPath + "Images";

            //Single Thumb - Properties available in free version
            oMediaManagerPro.Frame_Time = "5";
            oMediaManagerPro.Image_Format = "jpg";
            oMediaManagerPro.Image_Name = "Image_" + DateTime.Now.Ticks;

            ////Single Thumb - Properties available in full version
            //oMediaManagerPro.Width = 320;
            //oMediaManagerPro.Height = 240;

            //grab thumbnails
            MediaInfo oMediaInfo = oMediaManagerPro.Grab_Thumb();

            #region Print Output Information
            StringBuilder strOutputInfo = new StringBuilder();
            strOutputInfo.Append("Image Created = " + oMediaInfo.File_Name + "<br />");
            HttpContext.Current.Response.Write(strOutputInfo);
            #endregion
        }

    }
}

I have got these code from http://www.helpprogrammers.com/csharpsample.aspx

i have two more links, which may be help ful, but as a starter in .net, i am not that capable of understanding that code in the page...

http://nolovelust.com/post/Another-Simple-C-Wrapper-For-FFmpeg.aspx

http://jasonjano.wordpress.com/2010/02/09/a-simple-c-wrapper-for-ffmpeg/

thanks

shameer ali shaik