Make sure you have installed the latest QuickTime Extension for your
computer system and the PlugIn QuickTime 1.1. (or higher) for your browser.

Apple QuickTimes Home

Configuring your browser
(Under Netscape 3: Helpers/Under Communicator 4: Applications):

DESCRIPTION: QuickTime movie
MIME TYPE: video/quicktime
SUFFIXES: mov,qt,moov
HANDLED BY: QuickTime Plugin