If you search YouTube for "Windows 95 launch", you'll find many copies of this video:
This is commonly identified as having been recorded at the Windows 95 launch, but it wasn't. The Windows 95 launch featured Jay Leno and the stage looked like this. If nothing else, you can see that Bill is wearing a different shirt.
So yes, it's a bunch of people dancing like dorks, but it wasn't the Windows 95 launch. My guess is that it was some sort of sales event.
One of my friends remarked, "Sure, the dancing is horrible, but I don't think the dabbing generation is in any position to criticize another person's dancing."
Windows 95 released to manufacturing on August 24, 1995.
We'll return to the Alpha AXP tomorrow.