I can’t overstate how helpful the illustration is (with the play mode and the slide by slide mode). Thanks!
“If you recall, we have learned such a data structure, Disjoint Sets!”
If going through the topics/lessons from top down, then we haven’t visited the Disjoint Sets lesson yet. Maybe you could split out this lesson into one about “using multiple data structures” and then any lesson that requires multiple data structures could be moved there.
Note that the Minimum Spanning Tree is a concept that only applies to undirected graphs. I haven’t seen any mention of directed VS undirected in this page, but MST is only for undirected. For directed graphs the equivalent problem has a difference name (“Minimum-Cost Arborescence”) and uses different algorithms.