As you see our MBS FileMaker Plugin runs fine on WebDirect.
For that please install the server version (the one with 64bit included) into /Library/FileMaker\ Server/Database Server/Extensions and /Library/FileMaker Server/Web Publishing/publishing-engine/cwpc/Plugins/ folders. You need to enable plugins for the server and enable our plugin.
You can always using calls like MBS("Version"), MBS("Platform") or MBS( "Plugin.Path" ) to show details on the plugin.
PS: This is on Mac OS X. Windows version will come soon. Please contact us if you are interested.