Reference here: https://developers.google.com/youtube/reporting/v1/reports/metrics#Audience_Retention_Metrics
It says there are audience retention metrics for reporting APIs. However I couldn't find it in the existing jobs / reports, or if there's a way to retrieve this data via the API.
However, it is available in the Youtube Analytics API, however I can't imagine sending hundred of requests on daily basis to retrieve the data for each video in my channel.
I have searched all over the internet to no avail. Does anyone have idea how I could get this metric in the Reporting API or it just doesn't exist anymore?