I had a quick look at the source code and found that calls to these libraries ar made in src/vamps/k9ffmpeg.cpp like this one:
FormatHandle=dlopen("libavformat.so",RTLD_LAZY); So in order to avoid the error, one should install the four involved lib*-dev packages (actually, libavformat-dev and libswscale-dev will bring in the two others). I suspect this is probably not following the standard debian practices, in which case, this bug shoud be reported upstream. Let me know what route should be followed.