212: $replaceHTML = '<img src="' . $this->_placeholder_url . '" class="lazy lazy-hidden" data-lazy-type="iframe" data-lazy-src="' . base64_encode($iframeHTML) . '" alt="">';
Goal is reduce network request count to a minimum. Yes, this saves only one request, but that's how it goes - one at a time.
I can't off the top of my head think of any reasons why a backgrounded span, with 1px image base64 encoded in CSS, would not work here.
Can you think of anything, Bjorn?