$ sudo apt-get update
$ sudo apt-get install kffmpegthumbnailer 

kffmpegthumbnailer is installed in your system.

Make ensure the kffmpegthumbnailer package were installed using the commands given below,

$ sudo dpkg-query -l | grep kffmpegthumbnailer *

You will get with kffmpegthumbnailer package name, version, architecture and description in a table

kffmpegthumbnailer package basic information: