nonPublicMetrics

Non-public engagement metrics for the media content at the time of the request.

Requires user context authentication.

e.g.

"non_public_metrics":
 {
  "playback_0_count":1561,
  "playback_100_count":116,
  "playback_25_count":559,
  "playback_50_count":305,
  "playback_75_count":183
 }

Determine video engagement: how many users played through to each quarter of the video.