It would be great to have a developers source tarballs of matching ffmpeg/mtl/kdenlive versions in one package. And possibly one build script for them all, as configure parameters aren't trivial. This would be great.

People (possible contributors or betatesters) are repulsed on the very beginning by just fighting to build whole chain, to find matching and known-to-work together versions of the mentioned components.

MPlayer does the same with ffmpeg from the very beginning. It even discourages to use ffmpeg from CVS/SVN in favor of its bundled version.

I couldnot agree more! Have you ever tried to install QT just for starters?