I recently successfully ported my application using these tools. It sure made things easier. If you curious, the project is currently at hbfork.googlecode.com
There were a couple packages that I had issues with. Your version of mingw32-w32api is too old to build ffmpeg with. Ffmpeg requires 3.13 or better. There is no mingw32-pkgconfig, so configure would use the system pkg-config and use regular system include and library paths and flags. I found what I needed to fix these issues here: http://sourceforge.net/project/showfiles.php?group_id=204414 Is this project associated with your effort at all?
This may not be your area of concern, but MinGw has problems with large file support. They've had a ticket open for it since 2006 and a few patches have been floating around, but no resolution. I had to patch several things to accommodate.
FYI, the repository liked to from here is currently down: http://fedoraproject.org/wiki/MinGW