Just in case you missed it, I thought I'd share the unlisted reaction video to my reaction video.
Brady told me he had a new Parker Square video coming up on Numberphile and so I filmed a reaction video which was hidden as an unlisted video on the Numberphile second channel. If people watched to the end of the main video they would find it (or look at the pinned comment). I then made a second-order reaction video which was unlisted on my second channel.
But to make your life easier: here is the whole saga in one easy list.
0. Magic Squares of Squareshttps://youtu.be/Kdsj84UdeYg1. Matt Parker Reacts to Magic Squares of Squareshttps://youtu.be/U9dtpycbFSY2. Matt Parker Reacts to Matt Parker Reacting to Magic Squares of Squares https://youtu.be/tD2q2-_5Tyc