Haha, Andy and his shoelaces!
Aileen - there are some quite specific "rules" in this Harlem Shake thing - the comments below mention Andy reacting before he is supposed to!
Usually, a video begins with one person (often helmeted or masked) dancing to the song alone for 15 seconds, surrounded by other people not paying attention or seemingly unaware of the dancing individual. When the bass drops, the video cuts to the entire crowd doing a crazy convulsive dance for the rest of the video. The dancing style should not be confused with the original Harlem Shake dance. Additionally, in the second half of the video, people often wear either a minimum of clothes or crazy outfits or costumes while wielding strange props.  Typically, but not always, the video will end by converting to slow motion on the lion growl.
Thank for that. I didn't know any rules were involved. Trust Andy to get it wrong! lol