When in borderless/windowed, the intro can play in a small window

[CookiePLMonster]

Might be a bug new to Windows 11 as I don't recall seeing it earlier, but it's likely a D2GI issue that went under the radar. To reproduce the issue:

1. Run the game with the intro movie.
2. Move the mouse rapidly above the small window before it goes fullscreen. This likely clogs the Windows message queue with messages.
3. Observe that the intro starts in a small window. However, I can tell that this window renders in the desktop resolution, because the Steam performance overlay is tiny and distorted:
   

If the user doesn't move the mouse before the intro movie starts, it is properly fullscreen.

As a side note, is it possible to "differentiate" these intro movies from the in-game ones? If it is, perhaps they could be pillarboxed to 4:3.