You can rescan QuickTime Plug-in MIME settings from within your browser by doing the following:
1. Drag and drop the file Sample.mov installed by the QuickTime installer into your browser window.
2. Click and hold down the mouse button on the movie. A pop-up menu appears.
3. Select Plug-In Settings. The following screen appears:
4. To reset the MIME types the plug-in uses click on MIME Settings... The following screen appears:
5. Click the checkbox for the MIME type you want the QuickTime Plug-in to handle, then click the OK button. The following message appears:
6. Click the OK button twice to reach the Plug-In settings window.
7. Click Save to keep the changes you have made.