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Yes, it would be possible to decrease the page load time, you should only load what is visible on the screen, the others would leave for later. See if the Lazy load XT plugin in this link helps you:
https://github.com/ressio/lazy-load-xt
About the animation, it is very simple and quick to do, just put an image as background of your iframe through CSS.
http://codepen.io/dudaskank/pen/eBVpKw
CSS
iframe.loading {
/* imagem from search on google :p */
background: url(https://www.aiag.org/Content/images/admin_throbber.gif) no-repeat center center;
}
HTML
<iframe class='loading' src='https://www.youtube.com/embed/Zi_XLOBDo_Y' />
could put part of your code to help
– Alisson Diel