What are the ways to optimize page loading so that players are loaded only when the player is shown?

Question

YouTube

Good day!
There is a small block on the page, when clicked, a div opens on top of the entire content of the video slider.
The main page where such a slider is used takes a long time to load. In the Network FireBug panel, you can see that the site loads in 100ms, but the loading of the players themselves, the preview images of the video.
What are the ways to optimize page loading so that players are loaded only when the player is shown?

Answer 1

As I understand it, now you have the player code in a div and you only show it on click? Make the div empty and write player code to it only on click.