Anything before Thriller? Yeh, Probably not, Everything after? Probably was. I know most if not all his videos were shot on 35mm film, Smooth Criminal, as we know, is widescreen as was Thriller and probably Ghosts. In fact I have no doubt that most of them were filmed in widescreen and I think not releasing them is unacceptable.
35MM is a square 1.33:1, now what makes it widescreen is if you use Anamorphic lenses (usually 2.35:1 or you frame it using Mattes for 1.85:1).
Most of MJ's videos were shot with MTV in mind so they were framed full screen, there is a grey area with some films because of the matting, then in the late 90's letterboxing (the only way to see widescreen on a sqaure tv) became more acceptable with videos.
Just off the top of my head here is a list of the proper framing.
Don't Stop 'Til You Get Enough 1.33:1
Rock With You 1.33:1
She's Out of My Life 1.33:1
Billie Jean 1.33:1
Beat It 1.33:1
Thriller 1.33:1 tv version, Theater screenings in 84 were matted at 1.85:1. I'm unsure if Landis framed it this way. But the lighting flub in the graveyard may have meant to be matted off.
Bad 1.33:1
The Way You Make Me Feel 1.33:1
Man In the Mirror (1.33:1 for news/montage version/ Matted 1.85:1 Moonwalker version)
Dirty Diana 1.33:1
Smooth Criminal (1.33:1 tv version/ Matted 1.85:1 Moonwalker version)
Another Part of Me 1.33:1
Speed Demon 1.33:1 for news/montage version/ Matted 1.85:1 Moonwalker version
Come Together 1.33:1 for news/montage version/ Matted 1.85:1 Moonwalker version
Leave Me Alone 1.85:1 (because it was created using optical effects it has a fixed Aspect ratio, this is why even in Full Screen versions of Moonwalker it is letterboxed)
Liberian Girl 1.33:1
Black or White 1.33:1
Remember The Time 1.85:1
In the Closet 1.33:1
Jam 1.66:1
Heal The World 1.33:1
Give In To Me 1.33:1
Who Is It 2.35:1
Will You Be There 1.33:1
Gone Too Soon 1.33:1
Scream 1.33:1
Childhood 1.85:1
You Are Not Alone 1.33:1
Earth Song 1.33:1
They Don't Care About Us 1.33:1 Both versions
Stranger In Moskow 1.85:1
Blood On The Dancefloor 1.33:1 All versions
Ghosts 1.33:1 tv version/ Matted 1.85:1 theater version
You Rock My World 1.85:1
Cry 2:35:1
Now that HD/Widescreen tvs are the norm I would say that the proper aspect ratio for Moonwalker and Ghosts is 1.85:1 because that was the framing they choose for the theatrical versions.