The QuickTime extension must be present in the Extension folder of your System Folder in order for any of the example programs to execute. If you don't have a copy of QuickTime, search the online services or the Internet. Apple's ftp.info.apple.com site has this extension available for downloading, as do services such as CompuServe and America Online.
QuickTime movies run best when virtual memory is turned off. If movies seem to run jerky, and you have limited RAM and virtual memory on (or RAM Doubler on), try turning VM (or RAM Doubler) off. VM can be turned off from the Memory control panel. RAM Doubler can be turned off from the Extensions Manager control panel. Reboot, then try again. Movies should run smoother.