procedure TForm1.Button1Click(Sender: TObject);
const
 longName: PChar = 'f:\media\ANIM1.MPG'; {Your complete FileName}
var
 ret, shortName: PChar;
 err: DWord;
begin
 {Getting the short Name (8:3) of selected file}
 shortName := strAlloc(521);
 GetShortPathName(longName, shortname, 512);
 {Sending a close Command to the MCI}
 ret := strAlloc(255);
 err := mciSendString(pchar('close movie'), 0, 0, 0);
 {No error check because at the first call there is no MCI device to close}
 {Open a new MCI Device with the selected movie file}
 err := mciSendString(pchar('open ' + shortName + ' alias movie'), 0, 0, 0);
 shortName := nil;
 {If an Error was traced then display a MessageBox with the mciError string}
 if err <> 0 then
 begin
  mciGetErrorString(err, ret, 255);
  messageDlg(ret, mtInformation, [mbOk], 0);
 end;
 {Sending the "play fullscreen command to the Windows MCI}
 err := mciSendString(pchar('play movie fullscreen'), 0, 0, 0);
 {Use the following line instead of the above one if you want to play
    it in screen mode}
 err := mciSendString(pchar('play movie'), 0, 0, 0);
 {If an Error was traced then display a MessageBox with the mciError string}
 if err <> 0 then
 begin
  mciGetErrorString(err, ret, 255);
  messageDlg(ret, mtInformation, [mbOk], 0);
 end;
 ret := nil;
end;