I doubt it. It’s just a native video being offered to the browser using the “video” tag. To have a thumbnail image, it either needs …
a thumbnail image being set in the video tag, but that is not supported for attachments, as the images are not being processed on the server. They are just uploaded.
a thumbnail image being generated by the browser by (pre-)loading the actual video, but that’s not something the browser might want to do given the bandwidth requirements with potentially dozens of videos per page.
For proper video handling you would need to have a cloud package and use the gallery app. That will handle server video-processing now. Videos just being uploaded as attachments can be problematic. And preview images aren’t even the biggest problem as the entire video can also easily fail when the format/codec isn’t supported in the browser.