Seeking even with CoreAVC 1.5.0 (though they claim a lot of fixes which are not visible) with Gabest MP4 splitter is instable. Sometimes video freezes for a few seconds after seek by the time audio keeps going forward, sometimes after seeking the playback becomes much faster abnormally etc.
Complained here:
http://www.bsplayer.com/forum/viewtopic.php?t=13034