When trying to compile FFmpeg under FreeBSD 8.1-RELEASE I got an error:

Error: `ff_h264_cabac_tables+1024+128(%esi)' is not a valid 64 bit base/index expression

apparently the linker is broken, but as seen at Solaris ​here there is a workaround, also seen to work at FreeBSD ​here. After the ./configure phase apply:

 echo '#define BROKEN_RELOCATIONS 1' >> config.h

Trying this fix did still NOT solve my issue, next is trying a later/better compiler and linker, I will get the job done by clang/llvm for this matter: