GNU Gnash is open source Flash movie player. Current version (0.8.10) supports most SWF v7 features and some SWF v8 and v9. SWF v10 is not supported. Here you will find Gnash built for Kindle Touch (firmware 5.1.x). It also provides browser Flash plugin. You may use it with my port of SkipStone browser.
In GUI Launcher menu for Gnash there are options to enable or disable Gnash browser plugin. The plugin currently works only in SkipStone browser. Native Kindle browser also loads the plugin but doesn't display it correctly. Enabling Gnash browser plugin should be considered highly experimental. I recommend using this option only by advanced users. It may happen that on resources intensive Flash sites the plugin will restart or hang your Kindle.
Limitations of GNU Gnash plus bugs and limitations of its build for Kindle platform make this package very experimental. Only simple Flash projects work. There are problems with sound which often fail. However I hope someone will find it useful. I had a lot of fun playing simple games or using different utilities like for example this alarm clock :)
I prepared package to be used with YiFanLu's GUI Launcher or Unified Applications Launcher (for firmware 5.3 and higher). First install the Launcher, then download zip package from this page and unzip its contents to extensions folder on your kindle. Restart kindle, so that new item is visible in the Launcher menu. Start it from the menu.
Installation of this package doesn't change any system files on your Kindle. All the files are installed only in extensions folder. Enabling browser plugin creates link in /tmp/root/.mozilla/plugins folder. To uninstall Gnash disable browser plugin from Gnash GUI Launcher menu and delete "gnash" folder from extensions.