Billie Eilish made most of her new album with her brother's feet in her face.

The 22-year-old pop star writes and records her music with elder brother Finneas, 26, and during a joint interview on the 'First We Feast' YouTube series, she joked that much of the behind-the-scenes footage of her new record 'Hit Me Hard and Soft' is actually just of his grubby shoes.

Reading from a cue card, Billie asked her brother about "biggest argument" they had had during the production of herrecord, and Finneas replied: "I put my feet up on the desk a lot and Billie is right there."

With a laugh, Billie explained: "Finneas is always, well, not always, a lot of the time, he is a lot of times barefoot or a lot of the times in very filthy shoes. He'll put them...this is the situation...I'll be right next to them. And my face is right there.

"And we filmed so much of the making of the album that almost all of the footage is just his feet. The camera is right there and it's just his feet!"

In a serious answer to the question, Finneas noted that he learned not to be so "high and mighty" in telling the 'Lunch' hitmaker what to do when she was trying to compose new material for the album,.

He said: "I think the longest, biggest argument was during a period of transition in both of our lives when we were both just trying to be honest. To give you credit, I was very high and mighty and telling you you weren't being honest enough or authentic enough.

" And you were coming up with such beautiful melodies and cool cadences. Then, by the time we had cool lyrics, everything else was done. So I learned a lot from being too ego-centric."