nspluginwrapper is an Open Source compatibility plugin for Netscape
4 (NPAPI) plugins. It separates the execution environment of the
plugin from the browser, allowing a plugin compiled for one ABI to
be used in a browser compiled for another.

For example the linux 32bit Adobe Flash plugin can be used in a
native Firefox under Linux/x86_64, NetBSD, DragonFlyBSD and FreeBSD
platforms.

To install the Linux flash player into a native Firefox browser:
  - Also install multimedia/adobe-flash-player and
    multimedia/libflashsupport
  - Run "nspluginwrapper -i /usr/pkg/lib/netscape/plugins/libflashplayer.so"
  - Run Firefox

You do not need nspluginwrapper if the ABI of the plugin and browser are the
same, such as running a 32 bit Linux firefox and flash plugin under NetBSD.