Not a clue. Perhaps they're buddies with youtube employees. Your guess is as good as mine. A waste of a video frankly
Since youtube no longer limits uploads on time, only size (2GB, which can be surpassed if you go through enough hoops), I think they made the longest video they could at 2GB at the lowest bitrate possible by having only solid color frames, and uploaded it. Presto, obscenely long video.