How to view thumbnail preview in nautilus and dolphin in maverick 10.10

[user1]

I have two partitions with some video files in a folder on each.

When I open the folders I only can see thumbnail previews of the video 
files in one directory using nautilus, the other folder do not show 
preview of the video files in nautilus

In dolphin I can see no preview thumbnails at all.

Ordinary jpeg files seems to show thumbnail preview okay in both nautilus 
and dolphin.