LeetCode - Remove Nth Node from End of List | Solution Explained | C++

This is my O(1) space, O(n) time solution to the LeetCode problem - Remove Nth Node from End of List, explained in C++. This solution traverses the list just once. Few times I would have mentioned fast/slow node in the video when in fact that refers to fast/slow pointer respectively.

[smartswaggy]

what if n=4 and n=5. can u plz explain those cases.