How is “be on about” used?

In The King of Comedy (1982), one line is: “No point in going on about it. You know how I feel.”

Which movie is “be on about” from?

The clip at the top of this page is from The King of Comedy (1982).

No point in going on about it. You know how I feel.

4 作品で登場 · 1 本目

to talk about sth; to mean sth; to talk in a boring or complaining way about sth

くだけた · 非難 · 3 本の映画に登場

1
be on about sth
to talk about sth; to mean sth
I didn't know what he was on about. It didn't make sense.
2
be / go / keep on about sth非難
to talk in a boring or complaining way about sth
Stop keeping on about it!

定義：Oxford Advanced Learner's Dictionary 第 9 版