>>16356157/g/fag here. When google removed the ability to see dislikes om the youtube frontend, they didn't changed the API. That, together with youtube warning about removing it helped some pajeet to get all the dislikes to a database and with the addon inject some javascript (kinda like violentmonkey) to show the dislikes from the pajeet databasae instead of the youtube one. IIRC they have removed that from the API, but the addon now registers dislikes from the other users, and with that + some algorithm that tries to approximate the number of likes the video would had had if everyone had the addon (it gets the percentage of addon users that saw the video, how many of them disliked it and how many views and from that gets an approximation). that is how i think it works
