The .capx also has a reference to rex video as well as calljs. You might only use calljs, but the non-standard video plugin is still part of your project. so may be influencing it in some way (although I doubt it).
I just tried it from Dropbox(https://dl.dropboxusercontent.com/u/34306693/exportedIHJ/index.html), and I don't really get any messages either. The list just doesn't display, but this could be because the buttons only display (becomes visible) on successfully retrieving data from your site, which I doubt I can properly test.
I also tested the demo .capx that comes with CallJS (https://dl.dropboxusercontent.com/u/34306693/Cjstest/index.html)and it works fine, so the calljs plugin does work with firefox.
Hopefully, someone with more experience with this plugin will help you, as it does appear to be a problem with the plugin and firefox.