To play .swf files that require Version 9, you have two main options:
If you are working on an old operating system (like Windows XP) and need to fix a Version 9 installation: Intro to Flash Player 9 | Flash Reference Guide - Peachpit Macromedia Flash Player Version 9
It handled resources much more efficiently than Version 8. To play
Flash Player 9 was a major milestone because it introduced the language and the AVM2 (ActionScript Virtual Machine), which significantly improved performance. 1. Key Features of Version 9
If you are looking to work with for legacy projects or archival purposes, 1. Key Features of Version 9