Since you say you have already installed the 'Flip4Mac' component, you must have a valid 'QuickTime' folder somewhere on your drive.

If a 'QuickTime' folder does not aleady exist at the desired level, then create one - just be sure to name it correctly. If you only want it used locally, then place it in one or more of the user level 'Library > Quicktime' folders. Therefore, if you want the component to be available to everyone, place it in the root 'Library > QuickTime' folder. Components placed in these last folders are local and only available to individual users. In addition, there should be and additional 'Library' folder for each user account folder.

This 'Library' is available for use by all accounts available on your start-up system. There should also be a 'Library' folder at the root level of your start-up drive. One is located in your 'System' folder and should contain Apple components like the QT MPEG-2 component if you have purchased and installed it. Which 'Library' folder are you looking in? Basically, there can be a number of 'Library' folders. I don't see a Quicktime folder in Library on my computer.

Quicktime plugin for mac avi