$(document).ready(function() {
    $("#video1").addClass("selected_video");    // select default video
    
    $(".video_list_img").click(function() {
        // get selected id
        var selected_id = $(".selected_video").attr("id");
        selected_id = selected_id.replace("video", "");
        selected_id = parseInt(selected_id);
        
        $(".video_list_img").removeClass("selected_video");
        $(this).addClass("selected_video");
        
        // get clicked id
        var id = $(this).attr("id");
        id = id.replace("video", "");
        id = parseInt(id);
        
        var sign = "";
        var left = "";
                
        if(selected_id < id) {
            diff = id - selected_id;
            sign = "-=";
            left = sign + (diff * 640) + "px";
            $("#inner_content_holder").animate({"left": left}, "slow");            
        }
        else if(selected_id > id) {
            diff = selected_id - id;
            sign = "+=";
            left = sign + (diff * 640) + "px";
            $("#inner_content_holder").animate({"left": left}, "slow");
        }                                                    
    });
});