It's not even quite clear whether the brother helped his sister, pleasured her, or taught her. Either way, she should be grateful to him after a fuck like that. It's funny to see how he uses both his phallus and her toys to develop his sister's anal hole. It's bright and exciting, and you can see the details that are so valuable in a process like this. I wonder what he will turn her on with next time.
I have not yet seen them tie themselves, and so tightly, with knowledge. They seem to have it as a matter of routine, if not a weekly ritual before weekend lesbian sex.