On its pure surface level, not knowing any of the principals involved, this is simply a treat to watch. The reason it caught my eye, though, is because the main burly performer with a beard is Simon Russell Beale, who is one of my dad’s three favorite stage actors from my folks’ trips to London. (The other two are Michael Gambon and Henry Goodman. So, he has pretty good taste...)
Most people here probably don't have a clue who Simon Russell Beale is. (Not that it remotely proves anything, but the London newspaper The Independent has called him "the greatest stage actor of is generation.") Beale is an acclaimed and hugely versatile actor whose great-many roles include starring in Hamlet and Macbeth at the National Theatre, starring in Uncle Vanjya at the Donmar Warehouse, playing Iago in Othello at tte National Theatre, and also playing in musical comedy, as Dr. Pangloss in Candide at the National Theatre, and King Arthur on Broadway in Spamalot. If you saw any of the Hollow Crown series of Shakespeare "Henry" plays from the BBC, shown on PBS, he won a BAFTA Award for supporting actor playing Falstaff.
In addition, as the song develops, the last singer to come on near the end is the great opera star Bryn Terfel (who my dad and I saw in Sondheim's Sweeney Todd at the Chicago Lyric Opera -- a role he reprised last year that was shown on PBS, opposite Emma Thompson. .
Making this all the more fun for the live audience there is that the song is written in a way that gets the audience to keep thinking it’s over, and then keeps adding verses – and adding performers, which is part of the joke in the show.
Just to complete the record, the second performer in the number -- who starts out alone on stage with Beale, and who you see below -- is Daniel Evans, who starred as Candide in that same, aforementioned production which included Simon Russell Beale, so this is a "reunion" of sorts. And the third performer is Julian Ovendon, who has an extensive career on the stage and TV, but is probably best-known to audience as Andrew Foyle, the son of Chief Inspector Foyle on Foyle's War, and as Capt. Von Trapp in the live-British TV production of The Sound of Music that aired on PBS. (Well, it was live when it originally aired in England...)