That's how I hear it. I think that's called a descending line cliché... and kind of a standard turnaround technique. It might be valuable to see if there is another recording by another artist and see how someone else implemented it-- and maybe it's more audible, too.
My original chord choice was E7b9, and that may be a good enough sub, but I think the Dmin would be more "traditional"; the guy in the video lesson used one of Tomo's favorite F13 voicings, although I don't see how it makes "roman numeral sense" in this progression in the key of A.
I think a "3 Levels of Turnarounds", deep-dive lesson from Tomo would be a great addition to the Foundation series. There are slight variations in turnarounds based on whether it is jazz, rhythm changes, 12 bar blues, 8 bar blues, or jazz blues.
Turnarounds are a practical example of voice-leading, which could lead into lessons on how to choose triad inversions and chord subs to navigate through a progression and spice it up--and not just the ending. Maybe a little advanced for Foundation series, but an important topic to cover somewhere, maybe in "3 Levels" type of fashion, I think.