The "secret" to succeeding on YouTube is all about viewer satisfaction.
Here are 6 ways to actually measure if your audience is satisfied with your content.
If your content really is made for them and is good enough, people will come back. It will show better data once your channel has a certain level of traffic. Click "Analytics" then look under "Audience" to find this.
It might sound like a tip coming from 2016 but likes and dislikes are a simple way to know if people enjoyed your video. If you want to see it for a competitor's channel, use the "Return YouTube Dislike" extension.
If they are not satisfied with a part of your video or the clickbaity packaging (title + thumbnail), trust me, you'll see it in the comments. If you constantly see comments like "I can't stop watching" or "I got recommended one of your videos 2 hours ago and haven't left," that's a great sign.
If people enjoyed, they'll probably want more. Click "Analytics," then go to Advance Mode, then click the + sign to add a metric. Look for endscreen element click rate.
The higher the number, the better. Same path: "Analytics," Advance Mode, click the + sign. This tells you if people are watching more than one video per session.
YouTube will directly ask viewers if they enjoyed your video or not through satisfaction surveys. Although they can't be measured from your end, it's something to take into consideration. YouTube uses this data internally to decide whether to recommend your content.