Mine

dablade@RazorBlade:~/.stuff/testshit/gnashtest/gnash$ make dumpconfig | grep FFMPEG
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu --enable-libstdcxx-debug --enable-mpfr --with-tune=i686 --enable-checking=release i486-linux-gnu
Thread model: posix
gcc version 4.1.2 20061028 (prerelease) (Debian 4.1.1-19)
FFMPEG_CFLAGS is -I/usr/include/ffmpeg
FFMPEG_LIBS is -lavcodec -lz -lmp3lame -lxvidcore -ldl -lvorbisenc -lavutil -lvorbis -lm -logg   -ldts -lavutil   -lvorbisenc -lgsm -lavformat -lavcodec -lz -lmp3lame -lxvidcore -ldl -lvorbisenc -lavutil -lvorbis -lm -logg   -ltheora -logg
dablade@RazorBlade:~/.stuff/testshit/gnashtest/gnash$