next time check the thumbnails because you can see it clearly in the thumbnails
In this case, yes - you're correct. However thumbnails are not really reliable. Most of the time they are hosted on some off-site, spammy image hoster. Other times they don't match the encoded video (they are the correct video, but usually from the original encode that the watermarked version is encoded from). It's a crap shoot.
My opinion is that there should be a tag for non-watermarked videos (since at this point the default seems to be watermarked). Something like the old [HQ] tag for properly encoded videos. My opinion counts for fly spit in the ocean however...