Ubuntu Vibes posted a tutorial about installing the latest Flash Player in Chromium
Adobe is no longer releasing new versions of Flash Player for Linux with version 11.2 being last release.How to Install Latest Flash Player in Chromium
The only way to get latest Flash Player in Linux is to use Chrome, as Adobe has partnered with Google to distribute Flash player as a pre-installed plugin in Chrome. This plugin uses Pepper API in Chrome, which is unfortunately not supported by other popular browsers like Firefox and Opera.
However, in case you prefer Chromium over Chrome, this plugin can be easily used with Chromium.