To obtain the YouTube Data API key, you need to follow these steps:

1. Go to the Google Cloud Console: https://console.cloud.google.com/
2. Create a new project by clicking on the project dropdown at the top of the page and selecting “New Project”. Enter a name for your project and click “Create”.
3. Once your project is created, select it from the project dropdown.
4. Enable the YouTube Data API by navigating to the API Library. On the left-hand side, click on “APIs & Services” and then select “Library”.
5. In the search bar, type “YouTube Data API” and click on the result.
6. Click on the “Enable” button to enable the API for your project.
7. After enabling the API, navigate to the “Credentials” tab on the left-hand side.
8. Click on the “Create Credentials” button and select “API key”.
9. Copy the generated API key. This key will be used in the code to authenticate your requests to the YouTube Data API.