2.8 thumbs coming from different site

I have 2.8 running on two different web pages. When I embed videos on site #2, for some reason, the thumbs displaying for the embedded videos are coming from site #1. I searched through all my files for any cross references between sites #1 and #2 but there's nothing.

What files will I find where the thumbs are created from embedded videos so that I can see if I missed something in the configurations?

Also, is there a way to re-make the thumbs for the embedded videos? There's a way to do it for the uploaded ones, if I remember correctly...not sure how to do this for the embedded ones (other than manually uploading modified images with ftp).

OMG I just realized what happened. When I backed up my site after it was attacked by malware, I uploaded the thumbs from the wrong site. So...when a video is embedded, the thumbs are not overwritten with the new files.