Looks like piracy.h just contained a reference to a static blob (PIRACY) describing an 80x25x16 text mode screen. movedata copies it directly to the VGA screen base address (0xb800).

Since VGA text mode used one byte to select the character (from a font of 256 entries), and one byte to describe the character's attributes (16 colors aka 4 bits, bold, strikeout, reverse), the resulting buffer for an 80x25 display was 80x25x2 bytes, aka. 4000

When that's done, it waits for the user to acknowledge the anti-piracy message by pressing enter.

This is basically the early 90s equivalent of the "you wouldn't download a car" advert

I think the OP forgot the /s at the end of his comment.