Client libraries, as detailed in the videos, are important parts of any AEM implementation. You can use the HTML library manager to help manage your client libraries.
Go to system/console/configMgr and search for Day CQ HTML library manager. You can set up minification here by clicking the checkbox. It is a best practice to let AEM handle this, i.e. do not put any minified code directly in the client library. If you use the Debug checkbox, this will prevent the CSS and JS from being combined in one file and make debugging much easier.