You can do that in several ways.
With the help of analytics, you can check the performance of your video, here you can check how your video is engaging the viewers.
Also, there is an option on Video Page, where viewer can leave the comments to express his/her thoughts. You can manage all the comments, you can understand the liking/disliking of your audience easily with the help of comments they are leaving there.
You can understand more about comment management here - https://support.dotcompal.com/hc/en-us/articles/360029896471-Moderate-Your-Audience-reviews