(By the way, contrary to what the script and Meryl Streep say, the song wasn't remotely that "old" at the time. Originally recorded by Louis Armstrong, it was written by Bob Thiel and George David Weiss in 1967, which was only just 23 years before this 1990 broadcast. That's the equivalent of a song today having been written in 1994 and being called very "old" and that "it's been around a long time." In fact, if someone sang Billy Joel's "Piano Man," I don't think they'd introduce it even today as "Here's an old song, it's been around a long time" -- yet that was written in 1972, only five years after "What a Wonderful World." But I digress... )
This comes from a special on ABC called An Evening with Friends of the Environment. What's odd is that for some reason, Cher doesn't get a solo here. And Bette Midler gets two. The only thing I can think of is that this was recorded over a couple of days, and when it came time for the finale, Cher perhaps had a sore throat, but still wanted to join the group at the end and at least sing in the choruses. Though for an event like this, which appears to be a fundraiser, those usually are done live.
Oh, who knows? Regardless the reason, what a wonderful performance.