Vimeo or youtube video thumbnail (poster)

I haven’t been able to integrate any thumbnail or poster on top of my video.
I have been trying to copy-paste many code from codopen example without success.
Any ideas?

The video at the bottom on this site would be exactly what I want.
https://www.weaverskingdom.com/brics/swiper/index.html

Nobody has an idea about that?
It’s all around the web. But I think it’s done with wordpress.
What about doing this with blocs?

I have been trying hard to integrate codeopen code I found in past without any good result. But I was thinking about an example like this.

I am able to make the thumbnail disappear as you do but then, I am unable to start the video.
Are you able to start the video?

Sorry, I picked a bad exemple.
You are right, the video is not working in codeopen. But even when I replace the embed video, it doesn’t work.

Let’s try with this one. In blocs, it seems to work only with the youtube example, not with vimeo.