Every Mac running QuickTime 2.1 or below should use this extension, because it compensates for application that don't correctly pre-roll (prepare for playback) QuickTime movies (notably, all application created with Macromedia Director 4.0.3 and earlier). Apple's Multimedia Tuner 2.0.1 fixes problems with ISO9660-only CD-ROMs, adds compatibility with Systems prior to System 7.1, and improves system reliability under low memory conditions with Premiere and other multimedia tools. You should update to QuickTime 2.1 or newer, which includes the fixes in the Multimedia Tuner. QuickTime software can be found at: http://www.apple.com/quicktime/
