As you may already noticed, starting from OSX 10.9 Mavericks the QuickLook service cannot generate thumbnails and previews for some movie codecs like HAP or DXV in Finder - and not even for Quartz Composer files.

To solve this problem, we made a QuickLook plugin called QLVJ which using the good old Quicktime framework in the background to generate thumbnails and static previews for HAP and DXV movies - generating real previews for that kind of movies not possible due QuickLook limitations, so that function will show you thumnbail image instead. Starting from OSX 10.11, this plugin can generate thumbnails for Quartz Composer files too, but there is a bug in the Quicklook API so it won't work on some configurations.

QLVJ is a free and open-source plugin, check out the project's GitHub page for more info and download: https://github.com/lov/QLVJ