record a video in mpeg format through c# code

private Image CaptureScreen()
    {
        Rectangle screenSize = Screen.PrimaryScreen.Bounds;
        Bitmap target = new Bitmap(screenSize.Width,screenSize.Height);
        using(Graphics g = Graphics.FromImage(target))
        {
            g.CopyFromScreen(0,0,0,0,new Size(screenSize.Width,screenSize.Height));
        }
        return target;
    }

also use below link for one more example for video record through c# code

http://www.codeproject.com/cs/media/directshownet.asp (C#)