Plain Code

$('div.demo marquee').marquee('pointer').mouseover(function () {
    $(this).trigger('stop');
}).mouseout(function () {
    $(this).trigger('start');
}).mousemove(function (event) {
    if ($(this).data('drag') == true) {
        this.scrollLeft = $(this).data('scrollX') + ($(this).data('x') - event.clientX);
    }
}).mousedown(function (event) {
    $(this).data('drag', true).data('x', event.clientX).data('scrollX', this.scrollLeft);
}).mouseup(function () {
    $(this).data('drag', false);
});