There are two open-source Flash player implementations currently under active development. They are Gnash and Lightspark. (Another is Swfdec though development is almost stopped. In 2009, only 9 commits were made in the git repository).

Lightspark is available from the project's Launchpad page: https://launchpad.net/lightspark.

Gnash and Swfdec are available as Ubuntu packages from the Universe repository.

  Gnash can be installed by downloading the mozilla-plugin-gnash package.

  Swfdec can be installed by downloading the swfdec-mozilla package. 

Also: http://www.allwebdesignresources.com/webdesignblogs/graphics/flash-alternatives-ultimate-list-of-flash-like-animation-software/