If neither Swank nor Criterion has the film, your next step is to go to imdb.com. However, be aware that IMDB, while it is often useful, can also be problematic, for reasons described below.
Here's how to use IMDB: on the imdb.com site, look up the title of the film. When you've arrived at the film's webpage, click on "company credits" (on the left-hand side of the screen). On the "company credits" page, you'll see the distributor(s) listed. However, you're not done yet.
Once you have the name of the distributor, visit the distributor's website, and check whether the film is listed among their holdings. You'll find the web addresses of many distributors here on this page. If the address is not here, use Google to search for it.
If you can't find the distributor's website, or if you can but the film is not listed on their site, then the information you got from IMDB may have been misleading. One reason is that the distributor may have gone out of business. Another is that very often, multiple distributors are listed. There might be one distributor for the film and another for the DVD; one distributor for the U.S. but others for overseas; or the distribution might have changed hands a number of times over the years (this happens a lot!). An additional problem is that, generally, only theatrical distributors are listed. The two distributors that we use most often, Swank and Criterion, will not be listed at all.
Still, IMDB can be helpful and can save you a lot of time, especially for independent films and more recent films.
