To use YouTube TV first of all you have to obtain an API Key from Google’s Developer Console.
To obtain your API Key you can follow this guide using steps 1 to 3; Getting Started with the YouTube Data API
4. under APIs & auth > Credentials > Create new Key > (Select) Browser Key
5. (Recommended) Set any referrers to your domain to prevent unauthorized use of your key.
6. (Optional) Additionally disabling any other unused APIs that are enabled.
By visiting the intended channel’s Youtube home page. The URL should look like the following. Youtube username is “collegehumor”;
YouTube Channel ID
Channel ID is the alternative of the username. You can enter channel id instead of username. “UCPDXXXJj9nax0fr0Wfc048g” is the id of the channel on the following example;