How can an audio segment report an integrated loudness (LUFS) greater than 0
I did download this annoying video and analyzed the part with a vuvuzela. You should take a note that:

This part is clipped
The audio is stereo

And that pretty much solves the mystery.

If you calculate the loudness for each of the channels separately you will get approximately -1.4 LUFS. Since this is a stereo track you add those levels together. For incoherent sources, you would roughly expect a 3dB of boost. Lo and behold, the total loudness calculated from the stereo track is approximately 1.6 LUFS (+3.2).
If you think about it, this makes perfect sense. What happens if you take one of those clipped channels and play it back through a speaker? You gonna get some SPL. Now, add a second speaker and play the other channel, you would expect to be even louder (3dB louder to be precise). Therefore LUFS accounts for that.