Kibitz is also a term referring to circular commenting. One person comments, then the other person comments. A back-and-forth conversation outside the main issue, where the people having the conversation are not directly participating.
In computer science the term is the title of a programming language released by NIST, as a sub-project of the Expect programming language, that allows two users to share one shell session, taking turns typing one after another.
There is a 1930 film called The Kibitzer which is based on the 1929 three-act comedy play by the same name.
Jane Jacobs describes a kibitzer as someone who keeps a look-out on a street, and seeing suspicious activity, intervenes to help the victim. In this way, kibitzers help keep streets safe.