Consider enhancing selector/analyser workflow to accommodate labeling workflows

[breezykermo]

Mtriage can be a useful tool for scraping datasets and labelling them for machine learning workflows. Several flexibilities in selectors and analysers could be helpful here:

1. The ability in the youtube selector to automatically annotate videos returned from a particular search term, and to run multiple different searches using a single YAML config.

[breezykermo]

Machines aren't really good enough to do labelling solo, so if we really wanted to make this an effective labelling tool, we would need to add some interaction in the loop so that certain items can be filtered. Perhaps this could be built as an extension of some sort in the mtriage, or a postprocessing stage.