Notes are on my GitHub! github.com/rorg314/WHYBmaths
This video discusses the notion of continuity of maps between topological spaces. We see that giving a set a topology is the minimal structure required to define continuity, and how the choice of topologies on the domain and co-domain determines whether a map is continuous or not.
(Yes I stole this example from Fredric Schuller, but it illustrates the concept so nicely I couldn't help it!)