The Kodi people are not to be trusted on this matter, it's just an ugly political game. See http://forum.pine64.org/showthread.php?tid=1497&pid=13513#pi...
And also https://github.com/linux-sunxi/libvdpau-sunxi if you are actually interested in a working hardware accelerated video decoding. To sum it up, hardware video decoding acceleration works fine with fully open source drivers on Allwinner hardware, but the Kodi application just does not want to use them. Fortunately there are also other open source media players, which can do the job.
As for the lubuntu image, anyone can take any ARM Linux distribution rootfs and combine it with the Linux kernel, built for Allwinner hardware (both mainline and legacy kernels exist). You can find a lot of tutorials at https://linux-sunxi.org
But if you are not a very experienced user, I strongly suggest you to try something like the armbian distribution first.
As for the lubuntu image, anyone can take any ARM Linux distribution rootfs and combine it with the Linux kernel, built for Allwinner hardware (both mainline and legacy kernels exist). You can find a lot of tutorials at https://linux-sunxi.org
But if you are not a very experienced user, I strongly suggest you to try something like the armbian distribution first.