jrCore_media_player not working on my skin
Design and Skin Customization
Try adding this to your meta.tpl file:
<script type="text/javascript" src="{jrCore_javascript_src}"></script>
Then take a look at the meta.tpl file from one of the stock skins.
In your wowmusic skin I can see a lot of individual links to individual .js and .css files. One of the thing jamroom provides is a compression system where you can define all the .css and .js files that will be used in your skins:
/skins/(YOUR SKIN)/include.php
file and they will be compressed into a single file to speed up page load.
This allows modules to put .js and .css into the skin without alteration to the skin.
It seams like that's what's missing on yours.