I have a clean Ubuntu 15.10 installation these days. However, I noticed that video thumbnails (or previews) do not show up in Gnome Nautilus:
![Nautilus without video preview thumbnails](http://logan.tw/static/images/nautilus-no-video-thumbnail.png)
I prefer thumbnails to icons. Besides, I remember that Nautilus will generate a thumbnail for each video in Ubuntu 14.04. Thus, I took some …