I have a background video added to my website. Somehow, it automatically generated a data-poster-url with a .jpg taken as a snapshot from the video. I have no control over this .jpg, which is pretty annoying.
The reason it is annoying is, that google lighthouse (SEO) is telling me to use more or less a .webp format. Since I can not control the generated .jpg I can not increase my website’s performance.
Couldn’t say, it’s worth raising a ticket to support.
My library approach works well above. You could also build a reverse proxy to replace that attribute with your own URL content.
You could also ditch the background video element and build the same construction using custom elements. You’d need to handle any special mechanics that webflow.js does on your own, but you could still use the same Webflow video URLs if you like.