Um wrong. the "8" on the bottom doesn't mean the 8th note gets the beat. The dotted quarter gets the beat, while the 8th note receives the subdivision of the beat.
This guy uses incorrect vocab. "Duple" and "triple" refers to the time signature, not subdivisions of the beat. what he should have said is simple (2 subdivisions) and compound (3 subdivisions/triplets)
ear-gasm