Much confusion about the "My Passport Essential SE" Drive

I recently purchased a “My Passport SE” drive, and when WD SmartWare tried to detect my file types on C:, it detected gigabytes of movies, digital photos, email, and text documents.

The trouble is, I have no awareness of having installed any kind of media on C: at all. You think I would have noticed the dozens of gigabytes of music files, video files, and other stuff which SmartWare seems to think is on C:. I keep my media on external drives, and tend to install only Windows and applications on C:

I can’t seem to view the situation to see what SmartWare sees as a “movie file”, for example. Certainly, if there was one that big on C:, I would immediately move or delete it, since it shouldn’t be there in the first place. Same for files it thinks are “Email”, “Music Files”, and anything else we think of as “media” these days.

Thanks for any help you may offer.