Identification of triads using natural triad quality

Picked one by one from a mixed channel. Transcript check: both title readers certain; 5 of 5 sampled certain picks confirmed by transcript, none failed. Channel rule: Include only explicit instructional videos: music-theory or sightsinging lessons (e.g. 'Intervals - ...', 'Changing meters primer', 'Eyes and Ears Sightsinging N') and videos that explain a learning method ('Multiplication Memorization (and why it's not so hard)', 'Periodic table from memory using songs'). Exclude all songs, music videos, lyric videos, karaoke, performances and rehearsals.