I believe he is implying that Quicktime was the only app/codec/container that allowed the user to stop, rewind, fast forward, jump around in the clip without the app completely failing. As a video editor for the past 26 years, that has been my experience. Every other video playback app/container that I've used (on both Windows and Mac) failed at treating a clip in a non-linear manner. My current preference is still for Quicktime 7, the utility knife for video playback (even more so than VLC in my experience).