QuickTime is an
open standard container for timed
multi-media. It is free to
implement. The
NeXT guys made their own version of QT called
NeXTTime, based entirely on the contents of a forty dollar book published by
Apple. QuickTime forms the basis for the ISO
MPEG4 specification.
What is not free however, are the codecs used by Quicktime (Sorenson Video, Fraunhofer MP3, QDesign Music, Qualcomm PureVoice, Cinepak, etc). This is the major stumbling block for the implementation of QuickTime on other OSes.