Select Medial videos by tag

New feature. As admin. Required for controlled archiving / deletion.
As discussed this is a Priority 1 item. It should be delivered very soon aftyer the new version of Medial comes out in December(?). By the end of January? (Bug fixing permitting.)
Robert comments that we have a lot of one-time use cases, such as student video assignment submissions. These should be easy to identify and archive anyway. Robert also comments that a new architecture for storage and content delivery is on the rtoad map and will be much more affordable, to some extent mitigating the financial cost of poor deletion/archiving..

Discussed and agreed in the UVic-Medial meeting of 24.10.25