YouTube video source
To be able to offer YouTube video embedding on your site, you will need to get API key from Google. First you will need to create a new project in Google Developers Console. You may do so at the following URL:
After creating your project, make sure the YouTube Data API is one of the services that your application is registered to use. To do that you will need to click on your project name to select it and then on Library. In the list of APIs select YouTube Data API and make sure the status is ON for the YouTube Data API v3.
Now you need to create your API key. In the sidebar on the left click Credentials and then click on Create credentials. When prompted for the key type, make sure to select API key. You will be asked if you want to add some restrictions for added security. This is optional but recommended.
Once created, make a note of your new API key. Now go back to YouTube settings page on your site and fill in your API key in the appropriate text box.