Gnash is a GNU Flash movie player. Previously, it was only possible
to play flash movies with proprietary software. While there are
some other free flash players, none support anything beyond SWF v4.
Gnash is based on GameSWF, and supports many SWF v7 features.

- Gnash can run standalone to play flash movies.
- Gnash can also run as a plugin from within most Mozilla derived
  browsers, such as Firefox. Gnash also has support for Konqueror.
- SWF v7+ compliant
  Gnash can play many current flash movies.
- Gnash supports the viewing of streaming video from popular video
  sharing sites like Lulu.tv or YouTube.com.
- Gnash also supports an XML based message system as documented in
  the Flash Format specification.
- High Quality Output
  Gnash uses OpenGL for rendering the graphics on the desktop, and
  AntiGrain (AGG) for embedded framebuffer only devices.
- Gnash pays extra attention to all network connections, and allows
  the user to control access.

WWW: http://www.gnu.org/software/gnash/