I think there are two issues:
headers moved (no more ffmpeg/... )
http://blog.flameeyes.eu/articles/2008/03/01/warning-current-ffmpeg-subversion-will-likely-break-all-your-builds
and then the deprecated img_convert call. on and off ffmpeg versions
don't have that call anymore and then compilation/linkage breaks.
unfortunately the package management of ffmpeg packages is rather
strange and I have observed this function to appear and disappear
between versions. this was over the last year or so.
various things (vlc) sometimes need updates of ffmpeg and then you get
problems with these new changes.
in the old configure, libcvd configure tests for the headers (does not
find it), tests for the library (finds it). then it happily uses it as
an option and fails in compiling (headers not found). fixing the headers
in cvd/videofilebuffer.h allows compilation. now, linking to libcvs.so
fails because img_convert is not actually part of the libavcodec.so
library anymore :/ (even though its in the header :/)
of course, I don't think that anyone of us is responsible for any of
this or even has the responsibility to keep track of all these changes.
it's just the current state :)