The problem is that a function was renamed (see url). Attached patch fixes the problem; it replaces all occurrences of __av_freep by av_freep and removes the macro to translate from av_freep to __av_freep.
Created attachment 51283 [details, diff] Renames function, removes macro. This makes it build against ffmpeg-0.4.9_pre1 and breaks building against 0.4.7. Since the latest version is marked stable, vice should from now on DEPEND on >=media-video/ffmpeg-0.4.9_pre1.
new ffmpeg is going to to be marked stable since the current stable isn't working with the current stable gcc...
Latest ffmpeg is going stable in these days (actually, it's already stable on amd64) so this fix is getting more critical. Please apply this asap.
1.17 builds fine with latest ffmpeg.