Stand-in ≠ body double ≠ stuntman
Stand-ins are common and only necessary for prep work on the set, such as setting the white balance, exposure, so when the main actor enters the scene everything is ready to shoot. In MJ's case his stand-ins were Darrick Morgan, Earnest Valentino, among a couple of others. They are never intended to appear in the final product. They don't actually need to look like the main actor, a general similar look (height, hair/skin color, clothes) is enough.
Body doubles are intended to replace the main actor, mostly for different body features except the face. In MJ's case this is where E'Cas came into play (e.g.
Who Is It, because of MJ's absence). They are meant to appear in the final product.
Stuntmen do physically demanding or dangerous performances for the actor. They are meant to be in the final product but it should be carefully edited so you don't notice the swap. In MJ's case there are several examples, such as the
Smooth Criminal videoclip for This Is It and plenty more in various other short films, or even think of the rocket man to end the Dangerous tour shows.
I didn't say it was E'Casanova on the Teaser, his name is Earnest Valentino. The profile you linked to seems to be a fake one, though.
This is him:
https://www.facebook.com/EarnestValentino
www.facebook.com
