At last, after several months I was able to find the appropriate packages to get video thumbnails working!

Not sure about other distros, but in my case (openSUSE 12.3) there are two relevant packages: kde-mplayer-thumbnailer (seems to be part of KDE) and kffmpegthumbnailer (Packman repository). Both seem to have been added relatively recently, since I searched but didn't find any in 12.2 / KDE 4.9. I installed each of them, and enabled only the ffmpeg one in Dolphin - Preferences - General - Previews. Now all video files have a thumbnail when Previews are enabled

I am trying to get video thumbnails in Dolphin but can't.
And I am trying to install mplayerthumbs but it's in tar.bz format and I don't understand the instructions.
Please,help me to install this and thanks to you all.

Instead of downloading the source code (which is what you have done) I would suggest checking with your distribution package manager - it quite possibly has mplayerthumbs or ffmpegthumbs available for installation already.

MirceaKitsune wrote:At last, after several months I was able to find the appropriate packages to get video thumbnails working!

Not sure about other distros, but in my case (openSUSE 12.3) there are two relevant packages: kde-mplayer-thumbnailer (seems to be part of KDE) and kffmpegthumbnailer (Packman repository). Both seem to have been added relatively recently, since I searched but didn't find any in 12.2 / KDE 4.9. I installed each of them, and enabled only the ffmpeg one in Dolphin - Preferences - General - Previews. Now all video files have a thumbnail when Previews are enabled

I just today found this post and now was able to get thumbnail previews of all videos in Dolphin with openSUSE KDE 13.1 working.
Thanks so much for your persistence and effort. I was able to identify the files necessary files, set up the appropriate packman repo, install them and only enable ONE of the ffmpeg thumbnailers in Dolphin's preferences. (not the mplayer one). As if orchestrated the thumbnails appeared like dominoes in my window manager. Thanks!

Thanks for confirming that fixes the issue - I have now marked this topic as solved, which should make it more visible to future searchers.