I wouldn’t consider those files either. Since you did put them through iTunes, I would imagine them only being used within their respectable media apps (Photos, Music, and TV) unless otherwise accessible through API for obvious reasons.
You can put those videos in iCloud Drive or I’m guessing just save them in the ‘On My iPad’ section (which as of now isn’t functional yet) to be able to open them in different apps (also something that isn’t possible yet).
We really don’t know the extent of how integrated the Files app will be but I can certainly tell you that anything that will ‘puncture’ the sandbox will not possible due to privacy, security, DRM, etc.