Package: digikam Version: 4:5.7.0-1 Followup-For: Bug #834131 Since version 5.6.0 video thumbnails and playback are broken again (worked for me for the versions before with the libqtmultimedia packages).
Digikam release notes state that starting with 5.4.0 qtav is used for audio and video files, replacing libqtmultimedia. So I guess a rebuild is necessary to enable audio and video support again.