I am very skeptical. Something that requires four years of study at the Pontifical Institute of Sacred Music simply cannot be covered in a few months. He does not demonstrate the Solesmes style accurately in some of his videos, and he appears to neglect mensuralism and the medieval theorists altogether as unworthy of consideration—but of course so do the semiologists. They're sitting on their brains. Cardine, Agustoni, and Göschl are certainly worth reading, but so are Mocquereau, Vollaerts, Murray, Van Biezen, Floros, and many others. Spend your time and money elsewhere. I recommend Murray as the best starting point for serious study of the sources.