I agree this is a somewhat confusing question and could be worded better.
For reference to anyone reading this the relevant line from the video transcript is:
"The optional process can be tied to a stage as in the example described above where it can only be initiated in the Account holder information stage. Alternatively an optional process can be made available across the entire case."
The question is:
Which of the following statements are accurate when we define an optional Process? (Choose One)
Optional process can be defined specific to an assignment
Optional process is always triggered declaratively
Optional process can be triggered only in the stage where it is defined
Optional process can be triggered only by operators who have manager access
It is true that in the case where an optional process is defined on a Stage then it can only be triggered from that stage. It has to be specifically configured case wide to be accessible everywhere.
It may make more sense if the question said something like "Which of the following statements are accurate when we define an optional process on a particular stage?"
Actually when I review the configuration options for the case wide variant in the designer studio, optional processes don't even get called that, they get called "Case Wide Supporting Processes". See the screen shots below (These are taken from 7.1.7, but please note that the Stage / Case configuration UI has changed in 7.1.8)
Optional Processes are configured on individual stages:
Case Wide Supporting Processes are configured on case types: