The video shows the song
"Joy to the World" being created from a template.

The notes are specified by their name and octave, and their durations are specified either by a character code or by a numeric value.

They are entered here by picking from the graphic Treble stave within the popup editor.

When complete, you can export songs to MIDI and WAV files for input to music processing and music publishing applications.

The songs here were produced by opening the WAV files in Audacity and then exporting to MP3.