title: Measuring "Watch Time" for a video platform
body: <p>I have a video sharing service and I'm trying to track the watch time to provide recommendations. I have two questions here:</p>
  <ol>
  <li><p>What's a good way to measure this? One I've seen around the web is to send a tick every 10 seconds and increment some counter, but this seems very inelegant.</p>
  </li>
  <li><p>How should this data be stored for processing an analytics? Should each user's view of a video be a row in my postgres database for example? And the watchtime is incremented on that row as a series of 10s ticks? <code>timespent:5</code> = 50s?</p>
  </li>
  </ol>