To fetch live chat participants, you need a YouTube Data API v3 key. Here's how to get one:
- Go to the Google Cloud Console
- Create a new project (or select an existing one)
- Navigate to APIs & Services > Library
- Search for "YouTube Data API v3" and click Enable
- Go to APIs & Services > Credentials
- Click Create Credentials > API Key
- Copy the generated key and paste it into the API Key field
YouTube API Getting Started Guide
Google Cloud Credentials Page
Live Chat Messages API Docs