AFAIK the consensus is based on the credits block on the back of the DVD"Frank Miller's Sin City" -> Frank Miller's Sin CityFrank Miller's "Sin City" -> Sin CityPersonally I remove all possessivess localy because I wouldn't know in the first place whose movie it is. I'd look for "Sin City" under "S" and "The Birds" under "B", not under "A(lfred)" or "H(itchcock)".
When one of you comes up with the definitive answer, remember to Skip-ify it! If you type the word "RULES", "NO", or "YOU PEOPLE" it should be in capitals. All other words shuld be mispelt. Then threaten to leave/sulk/post-lots-of-smileys.
I don't use the possessives in the DVDP database - the title is one of the few locks I use. I alphabetize my DVDs by the title only, no possessives, and so keep the database the same.