There is no other side (blood warning)

Finally I can make a proper debut to Redcrow!
About to kill Jaguar, Rattuft takes away the opportunity from Brook (the leader of the rival group), causing the clan to regain the advantage when Jaguar managed to injure the other leader beause of that distraction. Later, Brook did not survive the injuries due to lack of resources.

In this short time, Redcrow finds Brook dying, as he believes that Redcrow is coming for him to take him to the "other side", which is true to a certain extent. Redcrow looks very calm and with a comforting voice tells him that it is true, but it is not what he expects. Many crows start to surround both of them, and Brook understands the situation with fear.

Copypaste form another video with the Dark Forest concept:
When a cat dies, it must reach StarClan before the crows find them, since being on the livng ground they are vulnerable to them. Cats that have committed crimes and are not accepted into StarClan are practically sentenced, as spirits have no defense against crows, unlike living cats.

Therefore, the Dark Forest does not have any cats inhabiting it.

Crows in the Dark Forest have the ability to come together to form familiar figures for cats and confuse them, such as a rabbit or another cat. Crows that are on the side of the living only hunt spirits and are uncapable on killing a living cat on their own (unless, of course, if its injured or weak)

Audio: Bojack Horseman