Add video explainer for use of each tool

[widdowquinn]

This was considered before the first (2023-24) presentation, but there was not time to implement.

This might be something to consider for the confidence-building introduction in #1 - so we are demonstrating how to use the tools and interpret with a straightforward identification, in each case. If we do this, then we don't need to explain the reasoning the students should be developing, when considering the Ochrobactrum/Brucella case.