- What do you mean, could have been?
- If Father hadn't interfered.

3 seconds sound clip from the Holiday (1938) movie soundboard.

You can hear this line at 00:19:00.290 in the Blu-ray version of the movie.

Quote context

[...]

- Now, don't you say a word about Leopold. He's very sensitive.

- Yours?

- Looks like me.

- Who's the musician in the family?

- My brother Ned.

- I think I saw him this morning when I first arrived. At least I saw somebody with a hangover.

- That was Ned. He could have been a fine musician.

- What do you mean, could have been?

- If Father hadn't interfered.

- Who performed on the flying trapeze?

- Oh, all of us. And a terrible cousin of ours named Seton Cram.

- He and I used to swing by our knees and spit at each other.

- Nice goings-on.

- I'm happy to say now, I rarely missed.

- There's Julia and I as kids.

- Say, she was beautiful even then, wasn't she?

[...]