There are a multitude of videos that do not have the webp thumbnail.
Paul Irish even mentions the unreliability in his code:
* Lo, the youtube placeholder image! (aka the thumbnail, poster image, etc)
* There is much internet debate on the reliability of thumbnail URLs. Weak consensus is that you
* cannot rely on anything and have to use the YouTube Data API.
I have not spent a lot of time with this, but I think there's no good and simple solution for this that includes webp. The easy and pragmatic solution is probably to simply forgo the webp version.
There are a multitude of videos that do not have the webp thumbnail.
Paul Irish even mentions the unreliability in his code:
https://github.com/paulirish/lite-youtube-embed/blob/a927d63781883088c185cb69a0baade52732ab3e/src/lite-yt-embed.js#L22
I have not spent a lot of time with this, but I think there's no good and simple solution for this that includes webp. The easy and pragmatic solution is probably to simply forgo the webp version.