Before the invention of YouTube comments, most people could make remarks that were slightly technically incorrect without fear of immediate public rebuke. The one exception was professors, especially if the classroom included an annoying student such as “Tom 7.” The invention of YouTube was doubly revolutionary: Now anyone can experience being a professor being corrected by an annoying student, but also, corrections can be made years after the fact, and at significant length, as the student cannot be told to “take this offline.” This video is such a lengthy correction and digression, and perhaps itself a fount of mistakes. Due to the esoteric detail and prodigious whiteboarding, it is almost a “Tom Academy” video. But since I grew a moustache to film it, it qualifies for the Main Sequence. Keywords: Gradient descent, half-precision floating point, linear operations, F=MA, rounding, exotic transfer functions, machine learning, MNIST, CIFAR-10, chess, fractals, Frobenius, cryptography, fluint8, Motorola 6502. For SIGBOVIK 2023. Paper, impenetrable code, etc.: http://tom7.org/grad/