You can do it with eventing, but it may look a little weird.
NO WAIT GOT IT
Make a map, go to the second layer, fill it with blank tiles. Chose a blank sprite for a hero and set position so the game doesn't bug you
As soon as the game starts - play movie.
The screen is black so a one second gap won't be much of a problem.
The other way is tinting the screen as the game starts but then the players will be able to see your map
<3 kitkat~
edit: If you didn't get what i said, tell me and i'll detail post~
MAJOREDIT
by the blank tile i dont mean the pink tile, sorry
I meant that black door type tile, which is in the second layer.
...
you know what i'm talking about right?