This is vague recollection at this point, but I do believe that the family did have knowledge of photography (my grandfather visited her 10+ years after this family became 'famous' through Russian press) and the father did not approve of their pictures being taken at first. I can see how that, combined with their deeply religious and isolated world view, could have been a cause for her superstition.
http://skeptics.stackexchange.com/questions/8380/did-some-cu...
"...the sin of television, which they encountered at the geologists' camp, proved irresistible for them..."
I agree that the account in the comments here did not give sufficient detail to determine if she had reason to connect something on a man's shoulder with the images she had seen in the television earlier, but she had some sort of prior exposure to video.
Sorry? It might as well have been a log on his shoulder.
Now, if it was viewing video of herself on this camera that brought a look of "pure terror" to her face (that you can't get out of your mind to this day, no less) I could begin to understand, but if she was watching a video replay on the camera, then how was it being recorded?
With no prior knowledge of video or photography what basis would she have for belief that the random equipment on a videographers shoulder would "steal her soul"?