This is a great tip for all pro users of the Avid DNX codec.
From Mavericks onwards it has not been possible to use Quick Look to preview Avid DNX Quicktimes. This great tip from janusz though points out that you can transplant the necessary Quick Look files from a Mountain Lion machine and voila… you can preview to your hearts content! There is also a link in the forum to the Mountain Lion files incase you don’t have access to them.
Magic Beans VFX - Jack Hughes 