That's the word "DID" in reverse form "DID YOU SEE THIS?", error making the video.
i had heard that explanation before. but i really don't think that is an error while making the video.
Given that no one has solved DID YOU SEE THIS X7 (unless it's one of the ones that were solved but we don't know the answer to), then the possibility is still open.
Im thinking the 'did you see this' clue has something to do with the 5 changing to a 2 on the side of the top coin at the start of the video.
Not sure whether the prize for that clue has been claimed or not though.
I'm skeptical of whether it actually changes from a 5 to a 2, or if it's just a compression artifact. I downloaded the 1080 resolution version from Youtube and watched it frame by frame, and still couldn't conclusively make out a 2 or a 6 after it seems to change.
Yeah you could be right there. I'm just baffled as to what else 'did you see this' could be...hmmm