Can Captivate use webp?

This trick is working.
Export your webp animation(s) into a static png file, then import it under captivate in your image placeholder(s).

Then when you publish your module, you can open the folder where the published files are exported.
Go to \Root\dr\, then you see all your medias contained by your module freshly exported. Just copy the name of the static png file you want to replace, copy/paste the webp file in this folder and rename this file as the previous static image deleted.
This works under Chrome, but I think it will work on all modern browers who supports webp images animations (so far most of them).
It's a quick a dirty way, but at least you can use the caroussel with animated images, which is what I was looking for.

Have a nice one mate.

No Webp nor Webm  format can be used in Captivate.

Files with the extension webp are images. The webp format is an open source format from Google. The video version is called webm. Adobe Captivate doesn't import either formats. You would need to convert them to one of the many formats that Captivate does import.  If it is a webp file you have you can open it in Microsoft Paint and then save a version of the file as a .png format. If it is webm (video) you can import that into VLC and then convert it to MP4.