Web Forms :: How To Capture Thumbnail From FLV Video

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.... how to get my code 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;

[CODE].... 

I have got these code from [URL]...

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

[URL]...

[URL]...