To kibitz is to meddle in a game played by others, to interfere with unwanted observations.
It is the Yiddish spelling of the German word “kiebitz” which is the name of a bird called a lapwing in English. The lapwing is a kind of plover, black and white, with an annoyingly loud call. Its name comes from the Old English “hlēapewince,” from “hlēapan,” to leap and a base word that means “to move from side to side” (from which we also get the word “wink”). The name is a description of the erratic way the bird flies. By the time of Middle English the spelling was simplified to “lapwing.”
Think of the kibitzer as the flashy black-and-white bird flapping around and making distracting calls.
By the way, the word “kibbutz” is an unrelated Hebrew name for a communal settlement.