is a "Smart Album".
This means that if a file meets the criteria set for the Smart Album, "media kind is music video" then it will automatically be placed in that Album.
No work required by you.

The 6 sections at the top of the left hand window are fixed. When clicked on, they display the contents of that particular media form.
All music in the Music Library, All movies in the Movies Library, All podcasts..... you get the idea.

It is only when you get down to the albums, that you can separate your tracks out.
What do you see inside that Music Video album?

P