> i.e., you accidentally clicked but have no idea where, and let's assume you have no idea of that particular checkbox's state prior to the accident
That the same for every single checkbox in every single form on the Web.
Even in the unlikely case in which you clicked on the lists button that opens the popin and then accidently clicked on a checkbox without seeing which one and without seeing the checkbox state change, you still have the list of lists on the screen and you can still choose if you do want this video in this list(s) or not.
> That the same for every single checkbox in every single form on the Web.
In my experience, the majority of forms on the web don't commit until you decide to submit, so if you have an accident before then, you can recover (well, buy a sense of certainty at the cost of redoing some work) by reloading the form. In contrast to that majority, here we're talking specifically about forms where each component auto-submits immediately. I think that if a component auto-submits, then anything related to that submission (success/failure status, undo, etc.) should be presented within that very component.
That the same for every single checkbox in every single form on the Web.
Even in the unlikely case in which you clicked on the lists button that opens the popin and then accidently clicked on a checkbox without seeing which one and without seeing the checkbox state change, you still have the list of lists on the screen and you can still choose if you do want this video in this list(s) or not.