Using Flash plugin
NW.js supports Pepper Flash plugin. Just put the plugin files (including ‘manifest.json’ of it) in the ‘PepperFlash’ subdirectory under NW.js binary. On Mac OSX, the subdirectory should be in the “Internet Plug-Ins” directory in the framework bundle.
The flash plugin loading can be verified with /path/to/nwjs --url='chrome://plugins'