You might have noticed that some of your videos no longer have a Finder preview in Mavericks. Macworld’s Chris Breen discovered that Apple has deprecated many of its older codecs in favor of the iOS-compatible H.264 and MPEG-4. To watch older video files, you must convert them with QuickTime X, install Apple’s professional codecs (if you bought Final Cut Pro, Motion, or Compressor), or use a more capable app like QuickTime 7 Pro or MPlayerX. follow link
Single Time Machine Backups
Tired of Time Machine running all the time? You can turn it off in the Time Machine preference pane, but still initiate a single backup by choosing Back Up Now from Time Machine's menu bar icon. Of course, your backup is much less likely to be up to date, but Time Machine won't be taking any resources while you're trying to work.
- ExtraBITS for 4 November 2013 (04 Nov 13)
Why Your Videos Won’t Preview in OS X 10.9 Mavericks