I use code like this:
[mejsaudio mp3="/wp-content/uploads/2013/01/01-The-Gift-The-Fight-320-Kbps.mp3" ogg="/wp-content/uploads/2013/01/01-The-Gift-The-Fight-320-Kbps1.ogg" preload="false" autoplay="false" volume="false"]
In previous version of the plugin on WP 3.5.0 autoplay="false" was working for all music inserts.
Now it is not working.
preload="false" was not working then and now.
Maybe You have some Idea about it what is not correctly working.
All best for You!