Mozilla's Shumway project appears to play SWFs without requiring a Flash player to be installed:
Shumway is an HTML5 technology experiment that explores building a faithful and efficient renderer for the SWF file format without native code assistance.
I'm looking at the source of their racing demo and can only see a link to a SWF and no JS.
How are they displaying this SWF without any Flash plugin being used?
Shumway loads, parses and executes SWF with JS, and uses HTML5 <canvas> to render it.
You can see a bit better what's going on behind the scenes when you open the SWF in the Shumway Inspector. Direct link for the racing game: http://www.areweflashyet.com/shumway/examples/inspector/inspector.html?rfile=../racing/race.swf