The Library class encapsulates the essential nature of a Ruby library --a location on disk from which scripts can be required.

The youtube_dlhelper is a short tool for download and manage the downloaded files. You are running the program inside the command line with a Youtube URL. Then it aska for a group name or interpreters name. Now it creates a Subfolder inside your Musicdirectory. Then it makes a MP3 from the downloaded file and moves it to the folder.