Hi
There was a problem with the file path which I have corrected in the file:
includes/functions/cs_av.php
it was mainly due to your directory structure being a bit different from the default oscommerce setup. This was the reason nothing was playing in the storefront. You will notice that I hardcoded your website address into that file to make it work, so it will only work for that specific site now.
But that wasn't the only problem.
The reason why only the first few seconds played before the clip stopped is to do with javascript. Javascript functions will stop Windows Media Player if they are called. Particularly in your product_info.php page (which I haven't altered), you have hardcoded javascript function calls for creating popups just above the WMP player. These are interfering with WMP.
As a test, try to temporarily disable javascript in your browser and see if it makes a difference. There is a way to stop the javascript interfering with WMP, but if you wanted me to do it, it would have to be a paid job.
I guess the good news is that the CineSound code wasn't at fault
Nick