A standard copy-and-paste YouTube embed lands on your page as an
<iframe> which loads a big ol' pile of other stuff to play that video. But the UX of it is still essentially an image and a play button. Click the play button and the video plays. You can build essentially the same thing with an anchor link wrapping an image!
Not long ago, we covered a very clever "lazy load" technique doing exactly this from Arthur Corenzan that was further improved by Remy Sharp and Adrian Roselli.
Paul Irish has tackled it as well with a
<lite-youtube> web component:
Provide videos with a supercharged focus on visual performance. This custom element renders just like the real thing but approximately 224X faster.