Whether the distant end of the loop is closed or not makes a difference eventually, where 'eventually' means once the initial EM wave has reflected from the end and returned to the load.
And considering the fact that Derek has a Ph.D. in physics education research [1] that seems like an odd mistake for him to make, unless it was intentional.
As another commenter pointed out [2] Derek's content lately seems to be tailored to the maxim of "Make people believe they're thinking and they'll love you. Make them actually think, and they will hate you." It seems intended to invoke incredulity rather than understanding, presumably because he's decided the former is more marketable - because providing incomplete understanding and phrasing things in a way that's just technically correct enough to invite flame wars boosts engagement and therefore virality.
Yet another commenter [3] invoked https://xkcd.com/169/, which I think is apt.
[1] https://en.wikipedia.org/wiki/Derek_Muller#Early_life_and_ed...
I understood even less after watching it I think..
(The fact that the loop is closed can't be relevant by simple thought experiment, because otherwise it implies you could get ftl signaling by having a switch on the physically distant checking whether the "tiny current" flows when you close the source)