How to get a user's Google+ ID from a YouTube channel ID

Question

I'm running a service where people can connect their Google account using oauth 2.0, and with YouTube permissions I can manage their channels/access their YouTube Channel ID.

However, my question is whether or not you can go backwards. i.e. How can you determine the Google Account Owner from a given YouTube channel ID?

Answer 1

Probably people can not get Google+ ID from YouTube API(v3). But even the channel owner did not create google plus account, you can know it in advance on the channel HTML document by using XHR or curl.

1. visit channel page.

   https://www.youtube.com/channel/UCL8ZULXASCc1I_oaOT0NaOQ

2. Catch Javascript object from Developer tool on browser at the page.

   ytInitialData.metadata.channelMetadataRenderer.ownerUrls

   [ "http://www.youtube.com/user/googlechrome",
   "https://plus.google.com/100585555255542998765" ]

3. Second one is always google plus address and the number is Google+ ID. You can get more info from ytInitialData at the channel page if necessary.

One example. https://www.youtube.com/channel/UCiQPrVjbUlZBWY0fVtvpoKg

About that channel id(UCiQPrVjbUlZBWY0fVtvpoKg) You can not get Google+ ID from YouTube API(v3), but you can get Google+ ID at the channel directly when you can access html document or read it. Even if the channel owner did not create google plus account, the Youtube already made Google+ ID together.