^-- see above... i absolutely abhor quicktime, and i can't stand installing it, but i have a few funny clips, and some shorts and movie trailers that i can only find in .mov format (like the whalebomb ...
.mov is quicktime's native format, therefore it will, by default, always save as a .mov file. If you want to save it as a .mp4 file, just choose "Export" instead of "save".