Talks about that? About 뒤에 왜 또 접속사가 올까.?
About 뒤에는 명사.
Their predators.
Isolated spots such as roofs of caves.
Take up??? For take-offs.
Underdeveloped hind legs.

In the lecture, professor explains why bats hang upside down. First, he talks about protection. Hanging upside down protects bats from their predators, because bats are inactive during day-time. They sleep in the isolated spots such as roofs of caves. Second, he explains that there are advantages for take-offs. They have underdeveloped hind legs and weak wings. So they can't gain enough speed to take off. But hanging upside down covers these problems.