I do indeed rip all blurays before watching, so this is correct, but I’ve never seen one of these before — it’s a separate file on the bluray containing just this text for a few minutes. Presumably it’s not linked from the bluray menu, so you’d not be able to see this file if you’re using a furniture bluray player.
Hidden files! Fun!
But I wonder what they thought they’d achieve with this? Presumably dastardly bootleggers would either just copy the entire bluray, including the menu. If not, they’d just leave this file off the new bluray? And do bluray bootleggers even exist any more?