QuickTime player can't play Flash media files (.flv) from YouTube and most other popular video-sharing sites. And what we need to do is find the workarounds to convert Flash videos into formats which are QuickTime-compatible, that is convert YouTube to QuickTime for playback on iMac (Mac OS X 10.5 Leopard, Mac OS X 10.6 Snow Leopard included), Mac Pro, MacBook, MacBook Pro, MacBook Air, etc.
YouTube Downloader for Mac – is a Mac OS X application that can be used to download YouTube FLV video files and convert them to QuickTime friendly format MOV.
1. Go to YouTube.com, the program will detect the video and download it while playing; or click Downloads>Enter a URL at the top menus to copy the video URL to download YouTube videos.
2. Go to library to check the videos which are planned to be converted from YouTube to QuickTime on Mac.
3. Choose "MOV" under the "Video Formats" section from the format list for the QuickTime playback.
Enjoy the YouTube show now, you have successfully convert YouTube to QuickTime on Mac OS X.
This YouTube Downloader for Mac could not only download YouTube to QuickTime, but also convert FLV files to practically any other popular video formats including MP4, MOV, AVI, ASF, 3GP, MPG, etc.