Comment 2 for bug 288418

I believe I have discovered why this is.

I decided to compile gimp-gap-2.4.0 from the source tarball at gimp.org.
Using all dev packages from the repository (9.10) for gimp and other dependencies, the build failed in file ./gap/gap_dbbrowser_utils.c line 160. Apparently (according to the comments) this function is a copy of one including in the gimp source header files. gcc fails because it doesn't know which version of the function to use and instead of using the local copy - it returns the error -> function already defined in _SOME_GIMP_HEADER_H and gives the file name. Why this function is copied from the gimp libs makes no sense to me, but removing the local copy of the function in gap_dbbrowser_utils.c (or commenting out) will result in a successful build.

My guess is that the package maintainer either mis-interpreted the error or has a policy of not modifying code and just disabled the offending module in the configure options. This disabled the ffmpeg video encoder support.