Dolphin
Introduction
Enable preview many file types. Install the required packages. Then in the settings of the Dolphin activate preview of selected file types.
Setup
Before start close the application Dolphin. Install the recommended packages. Note: calligra provides preview plugins for many offfice and graphics files.
sudo pacman -S --noconfirm --needed kdegraphics-{thumbnailers,svgpart} kdesdk-thumbnailers calligra
Additional plugins for less popular formats directly from AUR:
yaourt -S --noconfirm --needed audiothumbs kde-thumbnailer-{apk,blender,epub,fb2,geogebra,gimpresources,mmap,plasmoid,qml,webp,wmf}
If You want using mplayer instead of ffmpeg for generate thumbnails video files install and activate mplayer instead ffmpeg preview plugin in Dolphin Previews settings:
sudo pacman -S kdemultimedia-mplayerthumbs --needed --noconfirm
Open Dolphin. Go to Control > Configure Dolphin > General > Previews. Mark selected group of file extensions to enable them preview of in Dolphin. Save the changes to the settings.
Support
Official forum topic: [1]