Final answer:
The proper verb to complete the sentence is 'is,' conforming to the singular subject 'trilogy.' The complete sentence would be 'The trilogy of films, filled with stilted dialogue and boring musical interludes, is not worth your money.'
Step-by-step explanation:
The correct verb for the sentence 'The trilogy of films, filled with stilted dialogue and boring musical interludes, _______ not worth your money.' is 'is.' The subject 'trilogy' is singular, so the singular verb 'is' should be used. It is a common mistake to look at a word near the verb like 'films' and mistakenly use a plural verb. However, the actual subject is 'trilogy,' which is singular.