Logic-Sunrire brings us the news that a group of developers are porting codec libraries to homebrew Xbox360s (JTAG and DevKit).
At this moment, only mpeg1 work. The ffplay, ffmpeg and libxvidcore libs have been ported, but they still have to solve some issues with SDL.
When everything is finished and working, you will be able to find their project on a git or google code so you can freely use it. This will allow developers to integrate these libs into their own 360 homebrew projects (FSD for example) or use it to develop a video player for example.
The proof-of-concept binary has also been released. To test it, put a mpeg1 video named "test.mpg" is the same directory as the default.xex.