uses
 VfW { from download };
function GrabAVIFrame(avifn: string; iFrameNumber: Integer; ToFileName: TFileName): Boolean;
var
 Error: Integer;
 pFile: PAVIFile;
 AVIStream: PAVIStream;
 gapgf: PGETFRAME;
 lpbi: PBITMAPINFOHEADER;
 bits: PChar;
 hBmp: HBITMAP;
 AviInfo: TAVIFILEINFOW;
 sError: string;
 TmpBmp: TBitmap;
 DC_Handle: HDC;
begin
 Result := False;
 // Initialize the AVIFile library.
 AVIFileInit;
 // The AVIFileOpen function opens an AVI file
 Error := AVIFileOpen(pFile, PChar(avifn), 0, nil);
 if Error <> 0 then
 begin
  AVIFileExit;
  case Error of
  AVIERR_BADFORMAT: sError := 'The file couldnot be read';
  AVIERR_MEMORY: sError := 'The file could not be opened because of insufficient memory.';
  AVIERR_FILEREAD: sError := 'A disk error occurred while reading the file.';
  AVIERR_FILEOPEN: sError := 'A disk error occurred while opening the file.';
  end;
  ShowMessage(sError);
  Exit;
 end;
 // AVIFileInfo obtains information about an AVI file
 if AVIFileInfo(pFile, @AVIINFO, SizeOf(AVIINFO)) <> AVIERR_OK then
 begin
  // Clean up and exit
  AVIFileRelease(pFile);
  AVIFileExit;
  Exit;
 end;
 // Show some information about the AVI
 Form1.Memo1.Lines.Add('AVI Width : ' + IntToStr(AVIINFO.dwWidth));
 Form1.Memo1.Lines.Add('AVI Height : ' + IntToStr(AVIINFO.dwHeight));
 Form1.Memo1.Lines.Add('AVI Length : ' + IntToStr(AVIINFO.dwLength));
 // Open a Stream from the file
 Error := AVIFileGetStream(pFile, AVIStream, streamtypeVIDEO, 0);
 if Error <> AVIERR_OK then
 begin
  // Clean up and exit
  AVIFileRelease(pFile);
  AVIFileExit;
  Exit;
 end;
 // Prepares to decompress video frames
 gapgf := AVIStreamGetFrameOpen(AVIStream, nil);
 if gapgf = nil then
 begin
  AVIStreamRelease(AVIStream);
  AVIFileRelease(pFile);
  AVIFileExit;
  Exit;
 end;
 // Read current Frame
 // AVIStreamGetFrame Returns the address of a decompressed video frame
 lpbi := AVIStreamGetFrame(gapgf, iFrameNumber);
 if lpbi = nil then
 begin
  AVIStreamGetFrameClose(gapgf);
  AVIStreamRelease(AVIStream);
  AVIFileRelease(pFile);
  AVIFileExit;
  Exit;
 end;
 // Show number of frames:
 Form1.Memo1.Lines.Add(Format('Framstart: %d FrameEnd: %d',
  [AVIStreamStart(AVIStream), AVIStreamEnd(AVIStream)]));
 TmpBmp := TBitmap.Create;
 try
  TmpBmp.Height := lpbi.biHeight;
  TmpBmp.Width := lpbi.biWidth;
  bits := Pointer(Integer(lpbi) + SizeOf(TBITMAPINFOHEADER));
  DC_Handle := CreateDC('Display', nil, nil, nil);
  try
  hBmp := CreateDIBitmap(DC_Handle, // handle of device context
  lpbi^, // address of bitmap size and format data
  CBM_INIT, // initialization flag
  bits, // address of initialization data
  PBITMAPINFO(lpbi)^, // address of bitmap color-format data
  DIB_RGB_COLORS); // color-data usage
  finally
  DeleteDC(DC_Handle);
  end;
  TmpBmp.Handle := hBmp;
  AVIStreamGetFrameClose(gapgf);
  AVIStreamRelease(AVIStream);
  AVIFileRelease(pfile);
  AVIFileExit;
  try
  TmpBmp.SaveToFile(ToFileName);
  Result := True;
  except
  end;
 finally
  TmpBmp.Free;
 end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
 // Extract Frame 3 from AVI file
 GrabAVIFrame('C:\Test.avi', 3, 'c:\avifram.bmp');
end;