Youtube = {
  "timer": 0,
  
  "startAnimation": function(){
    if (!Youtube.timer)
      Youtube.timer = setTimeout(Youtube.animate, 1000)
  },
  
  "animate": function(){
    var thumbs = $(".youtube-thumb")
    thumbs.each(Youtube.nextThumb)
    if (thumbs.length == 0){
      clearTimeout(Youtube.timer)
      Youtube.timer = 0
    } else Youtube.timer = setTimeout(Youtube.animate, 1000);
  },
  
  "nextThumb": function(){
    var img = $(this);
    // yt thumb url example: https://i.ytimg.com/vi/0123456789A/1.jpg
    var src = img.attr("src") || ""
    var match = src.match(/\/vi\/([^/]{11})\/(\d)\.jpg/i)
    if (!match) return
    var v = match[1]
    var num = match[2]
    img.attr("src", Youtube.nextThumbUrl(v, num))
  },
  
  "nextThumbUrl": function(v, num){
    if (!num) num = 0;
    num = (parseInt(num) % 3) + 1 // cycle over 1,2,3
    return "https://i.ytimg.com/vi/" + v + "/" + num + ".jpg"
  },
  
}