I have been staring at this one for some time now. Checking the script from ‘DOM ready’, comparing the scripts (and CSS :-) ). But now I have found it!!!
HTML 5 data- Attributes
As of jQuery 1.4.3 HTML 5 data- attributes will be automatically pulled in to jQuery’s data object.
You are including 1.4.2, so the ‘data-pos’ HTML attribute is ignored. So, either include a newer version of jquery or change:
jQuery("#mover").css("left", -($el.data("pos") * speed - 40));
jQuery("#mover").css("left", -($el.attr("data-pos") * speed - 40));
BTW You can use ‘$’ to reference jquery while inside the :
I also don’t think you need to use the no-conflict mode of jquery. If you are still loading the script via the deregister/register scripting in the ‘function.php’, as it unloads WordPress’s warped version of jQuery (but leaves the original jQuery for admin pages!).
I could be wrong, on all accounts – but I have learnt a few things while playing :-p