Visitors never see this screen. This is the single OAuth client the app runs on — set it once and bake it into OAUTH_CLIENT_ID in app.js, then everyone just clicks “Connect YouTube”.

1. Google Cloud Console → APIs & Services → Credentials.
2. Create credentials → OAuth client ID → Web application.
3. Under Authorized JavaScript origins add:
   this site's origin
4. Enable YouTube Data API v3 + YouTube Analytics API.
5. Copy the Client ID (ends .apps.googleusercontent.com).

Paste it below to use it right now on this device, or hard-code it in app.js so it ships for every user.