It seems like nobody has created npm module to get prebuilt binaries for ffmpeg, ffprobe, ffplay and ffserver.
I went ahead and put something together quickly.
API and Node module
HTTP API: http://ffbinaries.com
Node module: https://www.npmjs.com/package/ffbinaries
Node module: https://github.com/vot/ffbinaries-api
At the moment it simply links to externally hosted archives containing binaries. In the future they will be repackaged into individual components and I will add automated unzipping in the npm module.
Issues and pull requests welcome.