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).

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

informal · disapproving · Heard in 3 movies

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 sthdisapproving
to talk in a boring or complaining way about sth
Stop keeping on about it!

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

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

Said in 8 films · #1