function ShowAVI(const AVI: TCommonAVI;
  const ParentForm: TForm = nil; const aCaption: string = ''): TMyCommonDialog;
var
  a: TAnimate;
begin
  Result := nil;
  if AVI = aviNone then Exit;
  if ParentForm = nil then Result := CreateCommonDialog(aCaption)
  else Result := CreateCommonDialog(aCaption, ParentForm, ParentForm);

  with Result do
  begin
    a := TAnimate.Create(Result);
    a.Left := 0;
    a.Top := 0;
    a.Parent := Result;
    a.CommonAVI := AVI;

    Result.ClientWidth := a.Width;
    if Result.ClientWidth < 200 then Result.ClientWidth := 200;
    Result.ClientHeight := a.Height;


    if ParentForm <> nil then
    begin
      if ParentForm.Width > Width then Left := ParentForm.Left + (ParentForm.Width - Width) div 2
      else Left := ParentForm.Left;
      if ParentForm.Height > Height then Top := ParentForm.Top + (ParentForm.Height - Height) div 2
      else Top := ParentForm.Top;
    end;
    if aCaption <> '' then Result.Caption := aCaption else Caption := 'Ждите...';
    Show;
    a.Active := True;
  end;
end;

var avi: TMyCommonDialog;
begin
...
avi := ShowAVI(aviCopyFiles, Self, 'Бла-бла-бла');
...
end;