Okay, I was very surprised by this one. There are so many things hidden in such very short video. Inattentional Blindness means looking without even seeing some of the obvius facts. Being focused on some elements we see it is easy to ignore other things, like a moonwalking bear.
A very detailed explanation of this phenomenon can be found at You Are Not So Smart where we can learn a lot of useful things about how we think and see the World around us. Behind these small documentaries is David McRaney, a journalist that has published an interesting book about delusion.