I addressed it a few years ago in "10 Things That Made Us Say 'Wow' Since the Dawn of Time":

MICHAEL JACKSON PERFORMS ON NBC'S MOTOWN 25 TV SPECIAL

For those of us who witnessed it, this moment is indelible. On May 16, 1983, mid-way through a lip-synched performance of "Billie Jean," Michael Jackson, a hyper-talented little nellie boy whose album Thriller was about to change pop music forever, unveiled a new dance move and blew the world's mind. Known as the Moonwalk, the move saw Michael taking a simple step forward, then gliding effortlessly backward across the stage and into the pop culture stratosphere. Never mind that Michael's earthshaking move had been swiped from inner-city break dancers, or that, in later years, this cute and charming black guy would be replaced by a pasty-white child molester. Michael Jackson's Moonwalk achieved what all great art aspires to—bonding his audience in awe, propelling its maker to new heights, and simultaneously making and improving upon history. Can Neil Armstrong's boring, actual moon walk of a decade and a half earlier even compare with Michael's dazzling artistic reinterpretation? No.

And Fnarf eloquently expounded on it in the comments to this post:

When Michael turned the world upside down at the Motown anniversary show, EVERYONE was watching: white, black, young, old, rich, poor and middle-class. I was a "punk rocker" then, or something like one; but although we had our Prince albums in rotation we were pretty cut off from black music; but the grapevine told us to watch, and we did, and Michael lit the world on fire. Truly, it was Elvis on Ed Sullivan, or The Beatles on Ed Sullivan; it was all anybody could talk about, and the punks bought Thriller just like the gay disco boys and the grandmothers with granddaughters did.

It's true. America's love affair with Michael Jackson was an amazing thing to behold. As for the instigating performance: It's a freaking lip-synch. And it's still fucking amazing.

(Truly, he'll never be better than this. He got so mannered, so fast...)