Show video watch time and completion rate in post statistics

Video is becoming the most effective way to reach frontline employees: it's quick to consume on mobile and works better than long text. As more organizations communicate through video posts, it matters more to know whether those videos actually land. Post statistics currently show views, likes and comments, but not how long people watch.

Desired solution: For posts that contain a video, the ability to see:
- Average watch time per video
- Completion rate: the share of viewers who watch to the end

Nice to have: - Where viewers stop watching (drop-off points)