I'm surprised it took them this long to do a song together. Chris Martin has been friends with her for a while now.
I see they have famed backup singer Merry Clayton on the album as well. I was just watching '20 Feet from Stardom' last week. Interesting and inspiring story.
I didnt understand much after he said the way it started..
He said originally they asked Bey to do BG vocals...but she sounded so good (on Up&Up) that they turned her vocals up in the mix (louder than normal BG vocals apparently). On Hymn for the Weekend, they asked to make it "more of a duet" instead of just doing BG vocals.
After that Chris just praises her vocal skills and humility.