procedure TForm1.SpeedButton5Click(Sender: TObject);
var i:integer;
begin
try
with form1do
begin
i:=file_form.FileListBox1.ItemIndex;
if i<file_form.filelistbox1.Items.Count-1 then
begin
i:=i+1;
file_form.filelistbox1.ItemIndex:=i;
mediaplayer1.FileName:=file_form.filelistbox1.Items;
if ((extractfileext(mediaplayer1.filename)='.dat')
or (extractfileext(mediaplayer1.filename)='.DAT')
or (extractfileext(mediaplayer1.filename)='.mpg')
or (extractfileext(mediaplayer1.filename)='.MPG')
or (extractfileext(mediaplayer1.filename)='.AVI')
or (extractfileext(mediaplayer1.filename)='.avi')
or (extractfileext(mediaplayer1.filename)='.MP3')
or (extractfileext(mediaplayer1.filename)='.mp3')) then