QuickTime is a video-playing application that is most commonly used on Mac computers. QuickTime can only play a limited number of file types, however. One file type that QuickTime does not support is FLV files. These are flash video files that allow video to be streamed over the internet. Many people like to capture FLV files for non-streaming playback. It is possible to play FLV files in QuickTime, but there is a process that you have to go through to make QuickTime recognize FLV files.
Download the Perian plug-in for QuickTime at perian.com. This plug-in will allow you to play FLV files through the QuickTime application.
Install Perian on your computer by double-clicking the install icon. The program will automatically be loaded into the QuickTime application.
Open an FLV file in QuickTime to make sure that Perian has been installed correctly. If Perian has been correctly installed, all FLV files will now be playable in QuickTime.