Kinda lame they used the punchline in the original tweet, even before the reveal.

Two billion dollar companies fighting over percentages = big brother in 2020.

Seems like it's broadcast in-game? I don't know much about Fortnite. But it's been 10mins.

It was just an exact copy of the famous Apple 1984 ad, except the guy on the screen had an apple for a head and the person who attacked the screen was a rainbow Fortnite character throwing a Fortnite donkey head staff

Yes, it was an in-game event via their Party Royale game mode. Should be up on YouTube relatively soon - it was only a minute or so long.