[eluser]csotelo[/eluser]
The example can go into your class or library Youtube_api {}, please read the official manual to learn how to create libraries correctly.
$CI->load->model('youtube_model');
This loads the data model that manages your queries to the data in your database
$CI->youtube_model->get_key();
$CI->youtube_model->get_user();
$CI->youtube_model->get_pass();
Are queries that must exist in this model, which will return the data you want.
"my_key" function is an example that shows that you can use that data in any other function or need.