I'm trying to upload videos to multiple channels via the Youtube Data API v3.
I can do it properly when uploading videos to the main default channel, however I can't when we try to upload them into a different channel which is part of the same Youtube account (so the OAuth2 credentials should be valid).
According to the docs, I've to pass to the API the following params: onBehalfOfContentOwnerChannel and onBehalfOfContentOwner when calling the endpoint: /youtube/v3/video/insert
The point is we don't have a clear idea about what is the onBehalfOfContentOwner value is. Is it the main email address associated to the owner? How we can obtain it? Is it required or not?Isn't enough passing only the target channel ID when uploading?
By the other hand, I created multiple channels from the Youtube CMS for partners, but I'm not able to retrieve them when calling the API via: youtube/v3/channels?part=contentDetails&mine=true
I can only see one unique channel (the main one).