These are filters for the libavfilter framework.

Hopefully they get integrated into ffmpeg but until then you have
 to do the following to get it working:
link the files to your
ffmpeg/libavfilter/

also link the vid.stab source directory
ln -s ...../vid.stab/src ffmpeg/libavfilter/

(for now, to find the include files
later we have to make an own lib with header files and so on)

add the following lines to the files in libavfilter/
allfilters.c

    REGISTER_FILTER (STABILIZE,   stabilize,   vf);
    REGISTER_FILTER (TRANSFORM,   transform,   vf);

Makefile

to OBJS = .... optstr.o

and further down
OBJS-$(CONFIG_STABILIZE_FILTER)              += vf_stabilize.o
OBJS-$(CONFIG_TRANSFORM_FILTER)              += vf_transform.o

and
configure ffmpeg with

--extra-libs="-L/path/to/vidstab/src/cmake -lvidstab"




