Yes, exactly right! Great job!
Technically, Sybil merely claims to "know all about copyrights," but if
she did, then she would know they only prove a date of registration
with the Library of Congress - Copyright Office.
And now for your clues...
Building upon the two previous clues:
ow are the character names derived?
Meaning, what do they all have in common?
(Well, almost all).
Examples: Sybil, Rebecca, Damien, Eve, April, Sam, Rosemary, Blair, etc.
Who from the clips is not on that list?
Where does that missing name from the credits come from?
Do a copyright search.