A very simple method to start scrolling Carousel automatically. The autoscroll effect will stop on any mouseover event on carousel.

You only have to set time interval between 2 scrolls in options (in seconds) : new UI.Carousel(“horizontal_carousel”,{autoStart:3});

Code change:

.......................

// Group: Options
options: {
},

.......................

// Property: autoScroll
//   Time in second between to scrolling
autoStart : 0

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/*
  Method: autoStart
    Scrolls carousel automatically until any mouseover event
*/  
autoStart: function() {    
  var scrollInc = this.options.scrollInc;
  if (scrollInc == "auto") scrollInc = Math.floor(this.nbVisible);   
},

// Init
this.autoStop = false;   
var dir = -1; // || 1

// Check timer initialization
if (this.options.autoStart <= 0 ) return;

// Stop executer on carousel mouseover
this.element.observe("mouseover", function() { this.autoStop = true; }.bind(this));

// Start Periodical scrolling
new PeriodicalExecuter(function(pe) {
}.bind(this), this.options.autoStart);

if (this.autoStop) {
  pe.stop();     
} else {    
}

// Get Direction
if (this.currentLastPosition() == this.currentSize()) dir = 1;
else if (this.currentPosition() == 0) dir = -1;

// Scroll
this.scroll(dir * scrollInc * this.elementSize);