User blog comment:BackToTheFuturama86/HAL 9000 vs GLaDOS. Epic Rap Battles of Villainy Season 1/@comment-4721185-20151020224656/@comment-5482968-20151020232006

If you want to be technical, the Shutterstock overlay could be seen as a reference to Tyler, seeing as he's a "projection" of the Narrator's, as well as Tyler's blink-and-you'll-miss-it appearances in random scenes before he's introduced.