YouTube videos rely on a lot of factors ranging from the number of views, like to dislike ration and several others. Factors such as like to dislike ratios can often be manipulated by what YouTube calls "dislike mobs". Dislike mobs are groups of people that visit a video with the explicit purpose of disliking it, regardless of the content shown. This sort of attack can have irreparable effects on some channels/videos, which is why the company finally wants to do something about it.
YouTube is working on a few potential new solutions, and it wants feedback from creators. Tom Leung explains in the video below are some of the ideas that YouTube is sitting on. One of the solutions illustrated includes having users who dislike a video explaining why they disliked the video via a drop-down checkbox. However, it seems unlikely to be used as it’s described as “difficult to build.” Even if it is implemented, it shouldn't bother most people who are out to mass dislike said video.
Another option is not to show the total number of likes and dislikes on a video, or even just making the number of dislikes private. The move will do little in the way of discouraging people from disliking a video. Besides, YouTube has been known to 'remove' dislikes off certain videos in the past, and if the number of dislikes are private, there'll be no way to find out. The only real option here is to axe the dislike button altogether, but that will very likely not go down well with the already disgruntled community.
An ideal solution lies somewhere between not removing the dislike button and still somehow figure out if a video is getting brigaded. One option mentioned in the comments of the video suggests the idea of only allowing the dislike button to be used if the user in question has watched a certain percentage of the video. Then again, that's only a minor inconvenience which is easy to bypass by simply watching the video in question.