This comes from an evening at the Hollywood Bowl which was a 1993 tribute to composer/lyricist Jerry Herman (who's in attendance and clearly -- and understandably -- having a wonderful time) called "Jerry Herman's Broadway." Why I wasn't there, I have no idea. But I'm so glad the video exists. It's not the whole concert, but a healthy 25 minutes of it.
It features Broadway performers like Tony-winner Leslie Uggams, Oscar-winner Rita Moreno, the original ‘Vera Charles’ from Mame Bea Arthur (who has one of my all-time favorite jokes about lyric rhyming) recreating one of her numbers from the show, along with Lorna Luft and Braodway veteran LeRoy Reams who rousingly starts the video and later does some surprisingly fun impersonation work. It's also notable for one particular, long tribute to Jerry Herman's most famous song. And a treat finale which includes George Hearn (for starred in Herman's La Cage aux Folles), Michael Feinstein, Lucie Arnaz, and Dorothy Louden.
From this 25 minutes, you can see how wonderfully they produced this tribute. There's nothing slapdash and thrown together. It's a well-thought out, terrifically staged evening, with even from fun surprises.