Is it possible to get all the channels associated with a logged in user account, using youtube\'s version 3 API (https://developers.google.com/apis-explorer/#p/youtube/v3/).
OAuth2 allows login in with only one channel, so that's not possible.
OAuth2 already gives user a choice to pick the channel they want to authorize and give access, so you don't have to implement it anyways.
Found the answer in YouTube's API Blog here:
http://apiblog.youtube.com/2013/06/google-page-identities-and-youtube-api.html According to this as I'm using Android with OAuth2 there is no native Android account switcher, and
the then the API will choose the “wrong” channel in some cases, or even no channel (e.g., if the personal account doesn’t have a channel).
So I've got two options When this happens, the user has two options to specify the correct channel:
Use the Advanced Account Settings tool to select which channel should be used. This is recommended when a user has one channel they want to use for all applications.
Set up login credentials for each of their Google+ pages, and specify those > credentials, not their normal Google Account credentials, for each application that needs access.
Both these options require the user to do something outside the boundary of the Android Application, so both solutions are not usable. Unfortunatly this piece of functionality will have to wait until Android has some better way of switching the channel for the user...