if bCapture.Caption = 'Capture' then begin
    fVideoInput.ShowModal;
    bCapture.Caption:= 'Stop';
    fVideoInput.Connect;
    // show info
    iView.IO.DShowParams.GetCurrentVideoFormat(w, h, f);
    Label4.Caption := Format('Capturing at %dx%d %s', [w, h, f]);
    // start capture
    iView.IO.DShowParams.FileOutput:= 'D:\test.mpg';
    iView.IO.DShowParams.Run;
  end else begin
    bCapture.Caption:= 'Capture';
    fVideoInput.Disconnect;
  end;

...

procedure TfMain.iViewDShowNewFrame(Sender: TObject);
begin
  iView.IO.DShowParams.GetSample(iView.IEBitmap);
  iView.Update;
end;