Imagine that you 're walking along the street and come across this rather suspicious scene.

Perhaps influenced by the graffiti on the wall, you decide to be a good citizen and call the police.

You take out your phone, dial up,

and explain that you can see a man breaking into a two door car.

The police ask you to stay where you are and keep an eye on the situation.

A few moments later you hear a police car approaching.

It stops, an officer comes over, and asks you whether anything has happened whilst you 'd been watching.

In fact, something big in the scene did change.

Did you spot it?

The man 's jacket is purple now, but at the start of the video it was this color.

Would you make a good eyewitness?

Oh, and did you see the two a's here?

Sometimes we all fail to see what's right in front of our eyes.