RtmpDump, win64

Install MinGW
sf.net/projects/mingw/files/Automated MinGW Installer/mingw-get

It is important that you download mingw-get and not mingw-get-inst. mingw-get-inst installs x86 GCC

Build RtmpDump

:: for Windows
:: Install MSYS
mingw-get install msys-base
mingw-get install msys-wget
mingw-get install msys-unzip
mkdir c:/mingw64
sh mount c:/mingw64 /mingw64

:: Install GCC core
wget "sf.net/projects/tdm-gcc/files/TDM-GCC 4.6 series/4.6.1-tdm64-1/gcc-4.6.1-tdm64-1-core.tar.lzma"
tar xfC "gcc-4.6.1-tdm64-1-core.tar.lzma" /mingw64

:: Install GNU binutils
wget "sf.net/projects/tdm-gcc/files/GNU binutils/binutils-2.21.53-20110731-tdm64-1.tar.lzma"
tar xfC "binutils-2.21.53-20110731-tdm64-1.tar.lzma" /mingw64

:: Install mingw64 runtime
wget "sf.net/projects/tdm-gcc/files/MinGW-w64 runtime/GCC 4.6 series/mingw64-runtime-tdm64-gcc46-svn4483.tar.lzma"
tar xfC "mingw64-runtime-tdm64-gcc46-svn4483.tar.lzma" /mingw64

:: Install zlib
wget "sf.net/projects/mingw-w64/files/External binary packages (Win64 hosted)/Binaries (64-bit)/zlib-1.2.5-bin-x64.zip"
unzip "zlib-1.2.5-bin-x64.zip"
cd "zlib"
cp -r * /mingw64

:: Install PolarSSL
wget "polarssl.org/code/releases/polarssl-1.0.0-gpl.tgz"
tar xf "polarssl-1.0.0-gpl.tgz"
cd "polarssl-1.0.0"
make CC=gcc APPS=
make DESTDIR=/mingw64 install

:: Build RtmpDump
wget "repo.or.cz/w/rtmpdump.git/snapshot/60218d0.tar.gz"
tar xf "60218d0.tar.gz"
cd "rtmpdump"
make SHARED= SYS=mingw CRYPTO=POLARSSL LIBZ="-lz -static" VERSION="2.4-git-60218d0-20110930"

:: Optional, build librtmp.dll
make SYS=mingw CRYPTO=POLARSSL LIBZ="-lz -static"

Links

ariejan.net/2009/10/26/how-to-create-and-apply-a-patch-with-git
mcuee.blogspot.com/2010/08/mingw-win32-installation-to-build.html
old.nabble.com/Problems-with-nsis.make-td31498592.html
repo.or.cz/w/msysgit.git/blob/HEAD:/src/mingw-w64/patch/zlib-config.patch
sourceforge.net/apps/trac/mingw-w64/wiki/GeneralUsageInstructions