This addresses ENG-10569, which is a continuation of the bug initially reported here.

1. I was able to reproduce the issue on master when I used a non-staff account to upload a video. Afterwards it no longer reproduced.
2. I tested both images and video.
3. I read the code closely, both on master and before the recent changes (D14512, D14566, D14574) to make sure I understood what was happening.
4. I confirm via media mission reports that processed media (both images and video) have a file:/// URI when `plan.action !== 'none'.