true, it definitely depends where you live. If you’re in the US then it’s definitely a case of most don’t work, because most elevators at this point have been made after 1990, but if you live somewhere else then it can definitely be a case of some, or even none

I’ve never used one myself but I’ve heard talk of various ones either A) taking the public (real) like number and extrapolating the dislikes based on an old like/dislike ratio available for the video from before the dislike removal (doesn’t work on new videos) or B) the extension includes a feature where the user can like/dislike the video within the extension and then the dislike number is extrapolated using the public (real) like number and the extension’s private like/dislike ratio. In either case the number is not connected to the “real” dislike count that YouTube would have access to internally