Ugh. This again. The Ben Eater drawing is wrong - the feedbacks are crossed.
Even with the ‘corrected’ drawing below, know that this is a latch, and it doesn’t work correctly. The output definitely does not toggle with J and K high.
Why? When both inputs are ‘1’ the output oscillates during the time that the clock pulse is high. This is because the two NORs form a pair of inverters wired head-to-tail. That, folks, is a ring oscillator, a useful circuit by itself, but not here.
tl, dr: It’s a junk circuit. Useless, except as a lesson of how not to design a latch.