Looking at CPAN IMDB::Film was last updated seven years ago in which time I'm going to bet it's more than likely that their HTML (and glancing at the module source it looks like this thing is just scraping HTML) has changed in the meantime. You can try to patch things yourself and then submitting patches back (but then again since it hasn't been touched in this long it may have been abandoned; you can ping the author to check of course).

(It looks like they (IMDB) do have an official API but the developer page says something along the lines of "contact us for pricing" so scraping may be the way you'll have to go for "unofficial" access.)