Access free movies on Amazon Prime by logging into your account and scrolling over the Shop by Department drop-down box in the upper left-hand side of the Amazon.com page. From the drop-down menu, scroll over the Amazon Video option. A side menu then gives you a number of options; select Prime Video to limit your search to only those videos eligible for free to Amazon Prime subscribers.
If you are only interested in watching Prime-eligible movies, navigate to the top of the page, just under the banner advertisement, and scroll over the Prime Video drop-down box. This box opens a menu that allow you to select Prime Movies, Popular Movies and other selections. You can also use this drop-down box to select television shows, documentaries and children's programming. All of this content is free to Amazon Prime subscribers, whether it is licensed content or Amazon original programming.
Alternatively, you can click on the main Amazon Video link from the Amazon.com homepage. This navigates to all of the video content Amazon.com hosts, including paid and Prime-eligible content. To limit your selections to Prime-eligible content only, navigate to the top check box at the right and select Amazon Prime Eligible only, which eliminates all other selections. Use this to further limit your selections based on the genre, age and other characteristics of the move you want to watch.