I couldn't have said it better.

His reference to the major scale as being alternately called "Diatonic" is very confused, as that mode is called "Ionian."

Also, for example, note the naivete of viewing a C Major scale as fundamentally outlined by a piano, while ignoring the interesting tidbit that the notes are named starting with A.

If the piano fundamentally outlines anything, it is the A minor (aeolian) scale, saying it outlines a C Major is no more accurate than saying it outlines a B Locrian.

Meanwhile, there's interesting stuff in there nonetheless.