Here's a few places you can look for some of the older movies featured on our site:
Many libraries carry a nice selection of older movies, especially classic feature films such as the older Disney titles. And if your library doesn't have them, chances are they participate in the national Interlibrary Loan (ILL) program. This means that they will be able to request items from other libraries around the country for you at no charge!
Quite a few of the movies that originated as books were very popular when they were first released. You may know some friends or even a teacher that has a copy of the movie you're looking for - so send out a quick request.
If you can't find it for free, you can always rent a copy of the film. Call your local video store, try one of the rent-by-mail programs (such as Netflix or Blockbuster) or steaming video providers (like Hulu.com).