C#

        private void button43_Click(object sender, EventArgs e)//Extract Button
        {
            backgroundWorker1.RunWorkerAsync();
        }

        private void button44_Click(object sender, EventArgs e)//Stop Button
        {
            backgroundWorker1.CancelAsync();
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            string outPath = txtExtBitmap.Text;
            System.IO.Directory.CreateDirectory(outPath);

            if (fg != null)
            {
                foreach (FrameGrabber.Frame f in fg)//error in this line highlighting "in"
                {
                    using (f)
                    {
                        picBoxFrame.Image = (Bitmap)f.Image.Clone();
                        f.Image.Save(System.IO.Path.Combine(outPath, "frame" + f.FrameIndex + ".bmp"), System.Drawing.Imaging.ImageFormat.Bmp);
                        //Application.DoEvents();
                    }

                    if (fg == null)
                    {
                        return;
                    }
                }
            }
            if (backgroundWorker1.CancellationPending)
            {
                e.Cancel = true;
                return;
            }
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                MessageBox.Show("Operation Cancelled");
            }
            else
            {
                MessageBox.Show("OperationCompleted");
            }
        }

[\code]