I have a Sony Handycam HDR-CX210, and I shot 10 minutes of footage continuously tonight. When I imported it into my PC, the Handycam's memory also included 80-ish JPG images that were stills from the video. Is that a feature I turned on accidentally? Or is that standard (to create periodic thumbnails or something)? I don't need those stills, and they take up memory (1.5 MB each x 80 = 120 MB).
The only function which does this is called Smile Shutter. Please have a look at the official manual at page 110.
You can disable it under:
Menu > Camera/Mic > Face > Smile Shutter