You can set which categories your Movie falls under at the point of upload, here.
If you have already added a Movie to your library, you can also change those categories or add any that you missed from your Manage Library page.
To change the category:
- you will have to click 'Edit Details' on the video you wish to change
- then navigate to the 'Select Categories' section within the newly opened window
- select the categories, then press OK
- once back to the 'Edit Details' area of the video, scroll down and press the 'Submit' button
