use my mod:
https://vborg.vbsupport.ru/showthread.php?t=314704
the one you're using most likely is out of date for this day and age browsers.
if its a MP3 player you are after, just leave out the MP4 code and only use the MP3 part of the code. you'll be fine using this, because ive installed on clients running vb3, vb4, vb5 and xenforo attachments MP3.
good luck.
p.s, if your not happy with html5 player, i have many flash style players tucked away if you need one.