a special directory list input which
creates a input for each file as it appears.

as edited video becomes available in that directory,
it becomes an input ready to take

What about a variation on the existing list input, but with path monitoring? I would think an "Auto Import" function could be added to that existing feature. Click the "Auto Import" button and a configuration list appears with two columns - a checkbox to temporarily enable / disable a paths monitoring, and the path itself. Paths could be added and removed from this list. I would imagine there would need to be some limitation on the number of monitored paths to keep resources in check.

Plus, using the list feature, you're not running the risk of adding a huge mass of individual inputs should someone dump a bunch of files into a monitored folder.