Windows Mmencode , Unix For Win32
"You can try Avidemux, but not the stable one. You should try the win32 version (yes, for windows) with "Wine". It supports H.264 and you must use the double arrow to find out the keyframes because you can[not] cut everywhere (due to the "long gop" thing...). But, as every software like this, you can do JUST CUTS otherwise it will render (in case of transitions, effects, ectc.). "
windows mmencode , Unix for win32