I think I know what you're saying... on the card, in a folder on the card, somewhere around there, etc.

, you have (for example) movie1.mov, then movie1_thumb.mov, then movie2.mov, then movie2_thumb.mov, then movie3.mov., etc., right

? This says to me that after some footage is shot, the camera duplicates the file into a lower resolution in order to better play/browse in their or someone else's software... or possibly onto a connecting video screen. My Sony does something similar except that it puts thumbnail photos in a separate folder (I think this is what it does - I haven't looked in ages because I don't pay attention to that folder

) so that you can playback through the camera to a TV via an HDMI cable. Never needed it, never used it

... but this is my guess ^_~ .....
Please correct me if I'm wrong

!