Since the keyframe animation changes Kdenlive needs MLT from GIT master later than Jan 31, 2016 or else one commit concerning keyframe animation cherrypicked. Using MLT from GIT master Feb 12, 2016, I got render crashes with this log when and only when running with openGL/Movit enabled:

Rendering of /home/luke/Desktop/untitled.mp4 crashed

[libx264 @ 0x7f256800c260] [Eval @ 0x7f2575e61140] Undefined constant or missing '(' in 'dct8x8' [libx264 @ 0x7f256800c260] Unable to parse option value "dct8x8"
[libfaac @ 0x7f256800ffc0] [Eval @ 0x7f2575e610f0] Undefined constant or missing '(' in 'dct8x8' [libfaac @ 0x7f256800ffc0] Unable to parse option value "dct8x8"
[libfaac @ 0x7f256800ffc0] Channel layout not specified

Build options for MLT were ./configure --prefix=/usr --enable-gpl --enable-gpl3 ,on my system this gives openGL and working Movit without specifying other options. Explicity enabling Movit seems to also enable VDPAU or have some similar effect. Explicit enablement of Movit or of VDPAU diverts rendering to the screen, yielding playback in a window and a zero byte file (again) at render. Not naming either one lets tthe older version work but the above render crash resulted with current code. At least 4 hours of work to find this, as usual I cannot supply a backtrace as I do not have the debugging symbols installed in all the libraries for this sort of thing.

On Feb 15, 2016 commit 2aff190824cd100e3017ff9170be4b4dc3f8a9ca to MLT git master reverted the commit that caused both this crash and corrupted Movit rendering in a newer Kdenlive version that did not crash the render job outright. As of Feb 15, MLT from git master is working again.