This is the rtmpdump utility (and librtmp) VisualStudio project ready to compile for Windows. The good thing is that OpenSSL and libz libraries and includes are already referenced and included in the project so you don't have to worry about that. The includes are in the "include" folder, and the libraries are in the "libs" folder. Credits
The original project is taken from: https://github.com/ValYouW/rtmpdump-vs
Just install Mingw in your Windows, open the Visual Studio project and compile.
Debug folder is filled with a Windows 8 x64 compilation, just in case you directly need the libs.