How can you get more granular stats for a livestream video? One option is to use Google analytics and google tag tracking.
https://www.analyticsmania.com/google-tag-manager-recipes/youtube-built-in/ has a great resource on how to set up a events with google analytics. I used this page as a resource when setting everything up but the client wanted more granular and detailed stats than what the original recipe provided. Instead of reporting progress in 25% increments I changed the trigger so it broadcasted events every minute.
Edit after client view: The data that was recorded from these events while useful, was limited in value based on the data they wanted to decipher. The problem is that many of the videos that they want to get data insights from are talks by many individuals and they would like to know which parts users watched or skipped more often. I struggled to find a great way to parse this data in google analytics, even if an event is triggered every time someone seeks in a video, I could not find an intuitive way to diplay this data to the client without building a custom solution. Will have to find a better solution.