Steps to reproduce:
1. Create an unprivileged user (no ROLE_ADMIN) that has privileges to create themes
2. Try to create a theme with a bumper video
The unprivileged user cannot upload any files when creating or editing the theme.
Unprivileged users that are allowed to create and/or edit themes should be able to upload files as required to create and/or edit themes.
Workaround (if any):
No workaround for unprivileged users