dont or ou

Question

Le film, ________ l'acteur principal est Jean Dujardin, a gagné un Oscar.  Why can this not be 'ou' (accented of course) rather than dont?. It seems to work grammatically.

Accepted Answer

Hi Chris,
Yes!   It (where) probably would work in English, but in french we need to express "of whom" The film "of whom / of which" the actor .....
This is why "dont" is the most appropriate.
This is how I see it   --  hope it helps.
Jim.

Answer

où is a spatial or temporal preposition (where, when). As Jim says, in the example you inquire about, you are looking for a possessive construction (of which).