Mandi talks about the Descendant (the Dc), the opposite of the Ascendant. The Descendant marks the start of the 7th house in the horoscope and, together with the Ascendant, forms the relationship axis.
Mandi explains how the Dc and the 7th house show how we relate to others and how we are perceived by others. Also, what we project onto others and what others project onto us.
To show how we interpret our Descendant and planets in the 7th house, Mandi talks about a chart with Gemini on the Descendant and Moon in the 7th house.