[jdig4240]

1 create the developer account
2. enable the youtube v3 api...use that dialog to create the oauth credentials first, and the consent screen, give a name then the api key.
3. I found it easiest to copy the keys and secret via the web interface in the app Enable the api configuration page, to enable this go to the 
Settings - API
 and enable 
Enable API configuration page

You should then be able to update your keys by visiting 
http://<IP of Kodi device>:<port>/api
The port used is 
Settings - HTTP Server - Port
 which by default is 
50152
4. Go to maintenance setting and clear the access_manager.json file before you restart
5. Restart kodi. Then do the login scripts. 
There is one part I am unsure of...somewhere in the oath setup about, you pick devices and access. I had to click to add zone access (otherwise its just email and profile). I do not know if that is required to run the app, but I enabled all the locked youtube. That means they will review it at some point, but you might not need to do that to get it to work.
when you reboot, you should get the 2 google auth screens.

One final hint, if you are doing it on multiple devices, after the first is set, use file manager to copy apikeys.json (or whatever it is called) to a network location so you can just add that to the next kodi box. I believe the file is in profiles/add_ondata/plugin.youtube.whatever. That saved time doing my 4 boxes as you just copy that file to the new device using filemanager, then start at step 4 above, saves you all the cut and pastes, restart and do logins. If I think of anything else I will add it, but once I figured it out, got all 4 boxes up in about 7 or 8 minutes. On my devices where I just copied the files, I did not change user status at all, becuase wiping accessmanager I think does that anyway. I will try it out more later but hopefully that solves your problems. 

this does not work for me. I cant enable the youtube v3 api.
But it asks for a 12 month subscription and also asks for my credit card.....
WTF?!?! 
You can only use this addon with a payed developer Account now? whats that shit? are you kidding me?
And the whole Page is different than the one in the tutorial...
Can anyone tell me how i can get those Api keys without giving my Credit card/paid subscription?  

What a Douche you sound like.  People need to calm down and read a few pages in this thread.