Why don't my COUNTER reports and User Engagement Portal show the same number of playbacks?

COUNTER reports show higher number of playbacks than the User Engagement Portal because the former counts "playback" and the latter "aggregated_playback". An "aggregated_playback" only happens under any of these situations:

  1. When the page is refreshed after playing 30 seconds or more.
  2. When the user navigates away from the page (which means a click of any link to jump to another page).
  3. The user closed the current playing page or closed the browser window.
  4. In a playlist, a playback changes to a different (work-level) item. So it sends out previous aggregated_playback events (for the previous item played) immediately.
  5. When the player is done playing all items in current video or audio (this means it will trigger the aggregated_playback  at almost the last second of the media).