lavtools : mjpeg utils and avcodec frame based video editing tools and ffmpeg filters ( http://silicontrip.net/~mark/lavtools https://github.com/silicontrip/lavtools )
mpvguihs : A minimalist mpv GUI written in I/O heavy Haskell ( https://github.com/sebadoom/mpvguihs )
nordlicht : library + tool that creates colorful video barcodes ( https://github.com/blinry/nordlicht )
smplayer : Great Qt GUI front-end for mplayer/mpv ( http://smplayer.sourceforge.net/ )
x264-encoder : A free commandline encoder for X264/AVC streams ( http://www.videolan.org/developers/x264.html )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a multimedia
For Paludis use this rsync : rsync://gentoo.zugaina.org/multimedia-portage
If you have a problem : ycarus(-at-)zugaina.org