I found a random part of my car. I don't know where its supposed to be?

I own a 2013 ford convertible Mustang and while cleaning inside my car I found this part. Can anybody help me by telling me where this part is supposed to go? I found a random part of my car. I don t know where its supposed to be

It's the fuse box cover, and fits under the dash in front of the right hand door.
Here's a video to show where it goes:

http://www.carcarekiosk.com/video/2013_Ford_Mustang_3.7L_V6_Convertible/fuse_interior/replace