A legal version of MMF2 Standard or MMF2 Developer of the current build (right now 251) and the SWF Exporter.
If the extension is only a DAT, no nested folders, it goes in the Data\Runtime\Flash folder of your MMF2 folder.
But again, I'll emphasize: Use build 251.
Most of these extensions don't have a C++ version, meaning they only work when built. Be sure to build-test some of these extensions before you report any bugs or lack of functionality.
Also, if the extension doesn't show up, make sure you're using build 251.
Link is over there --------------------------------->
(This post is meant to help those that don't know this already, as I've seen too many posts saying things like "It doesn't even show up" in this subforum)