As far as I understand, the OP is looking for
and the YT-API can deliver:
what would help for this request.
To use the API - for example with the mentioned WSS - you need to register your own API-Key with your own Google account first.
The YouTube-WSS includes some code for the "publishedAt" API metadata:
and fills content into the YEAR field.
You are right: This information is not embedded in the video itself. Only with access to the additional API you can query such additional metadata.