All it does is send your command from a text field to a running tmux session. If you want to `brew update` without getting in the way of Netflix on your little laptop screen, it will do that. If you need to check up on it, just connect to the session from another terminal (or use one of the provided scripts so you can attach to it via the hotkey).

For another comment on how to use it, see below in reply to caiob.