This lesson comes from my Method Book Volume 2.
Below is the lesson for D Minor (Page 31) including the scales and chord progressions. The lesson for the Riguadon by Rameau (Page 32) starts 4:10 mins. The lesson for Leccion No.55 by Sagreras on (Page 33) starts at 6:20 mins. Be sure to watch the whole video straight through to get an overview and to not miss any info.
Below is a recording of the duet with my friend Natasha Pashchenko. If you are playing the duet without a teacher just play the top line on its own.