Louis is hungry. Look at those veins! This is near the end of the interview.
lunchiemunchies: #THEY HAD TO GO UPSIDE DOWN FOR THE MAKEUP ARTISTS TO FIND THE VEINS #YIKES
^This is correct, actually. Before filming every night, they had to sit upside down for about an hour so the veins could be traced with blue tattoo ink. So those are really where his veins are!