This article introduces a method to display video thumbnails in Linux and Ubuntu.
sudo apt-get updatesudo apt-get install vlcsudo apt-get install ffmpeg ffmpegthumbnailer gstreamer0.10-ffmpegsudo rm -rf ~/.thumbnails/* ~/.cache/thumbnails/*
sudo cp /usr/share/thumbnailers/totem.thumbnailer /usr/share/thumbnailers/totem.thumbnailer.bak
sudo nano /usr/share/thumbnailers/totem.thumbnailer