QuickTime player 7 supports older media formats such as QTVR, interactive QuickTime movies and MIDI files. It also accepts QuickTime 7 Pro registration code, which turns on QuickTime Pro functions. This QuickTime Player version is not supported and is provided to ensure compatibility with legacy media workflows for macOS Sierra and older.
QuickTime Player 7 won't work with future macOS releases.
You can learn how to use QuickTime Player (version 10), which is included with macOS , here.
Version 7.6.6:
Note: This product is not compatible with macOS High Sierra and later.