In 100 Most Metal Moments, go to the part where they're taking about Judas Priest being sued for the subliminal messages. At one point, there is an attorney saying something similar to, "We're suing because there is subliminal messages in the songs" or something to that effect. The black or brown square in the upper right corner flashes something white. If you play the part slowly, you'll see that it says "Subliminal Message", just to be funny. And there is the easter egg.