Make it clear in the "About" dialog that this version is using libav, not FFmpeg (to avoid confusion, especially in bug reports).
Clean-up: Remove unnecessary comment from debian/rules file.
Update "Build-Depends": After the fixes for Libav 10 (in commit 7bf48cda) the package doesn't build with Libav < 10 any longer.
Fix memory leak: In libav the allocated frames have to be deallocated using av_frame_free instead of the generic av_free.