Back in the days of OpenSUSE 11 or 12 I think, video thumbnails worked in dolphin.
Then, a few years ago, they stopped working, regardless of the plugin (kffmpegthumbnailer, ffmpegthumbs and the like) you used and irrespective of whatever trick I tried. This has been true for all versions of openSUSE I tried since then, on at least three different hardwares (laptop, netbook, desktop).
A week ago I set up a fresh HP business PC in my office and installed openSUSE Tumbleweed, in which, to my surprise, ffmpegthumbs are preinstalled. I thought this must mean that they finally work, but they DO NOT.
Since I did not touch anything configuration-wise, this must be related to my locale or my evil aura, because I simply do not get what it should be that I am doing wrong for years that breaks this.