You can see average video-view duration metrics in the:
- A) Google Analytics
- B) the “Audience retention” tab in YouTube Analytics
- C) reports in AdWords
- D) the “Campaigns” tab in AdWords
Explanation:
You can use the Audience retention report to get an overall measure of how well your video keeps its audience. Use the report to see:
- Average view duration for all videos on your channel
- Top videos or channels listed by watch time
- Audience retention data for a specific video for different timeframes
- Relative audience retention for a video compared to the YouTube average for similar videos
Read more here: https://support.google.com/youtube/answer/1715160