The performance is from MisCast 2016, which appears to be an annual fundraising production in New York. It features Tituss Burgess and Tina Fey singing the song, "You're Nothing Without Me," from the Tony Award-winning Best Musical City of Angels that has a score by Cy Coleman and David Zippel, with a book by Larry Gelbart. What's tongue-in-cheek here is that in the original show, the song is duet sung by a screenwriter and the character he has created.
It's an admirable performance by Tina Fey given that Tituss Burrell is an accomplished Broadway performance, known for his powerful (and high), soaring voice, who starred in the productions of The Little Mermaid as Sebastian the Crab (who of course sings the show-stopping, "Under the Sea") and played Nicely-Nicely in the Broadway revival of Guys and Dolls, singing the big production number, "Sit Down You're Rocking the Boat."
Not surprisingly, he's terrific here. And to her great credit, Tina Fey -- while out of her depth in comparison -- holds her own.
(Other performers are sitting on stage, and those with good eyes that wander from the main action will notice Lea Salonga, the original star of Miss Saigon, who also was in Les Miserables and the remake of Flower Drum Song. She's most prominent at the 2:08 mark sitting off to the right.)