Betty, I've a feeling that this is a bug in Scribus.
The workflow I recreated the issue with is as follows:
* Create an image frame.
* Put an image into it.
* Open the Scrapbooks palette.
* Create a new scrapbook.
* Copy the image frame to the scrapbook.
* Drag the "image" from the scrapbook.
A new image frame showing a red cross and the image name is created like you said.
Looking within the scrapbook itself, the SCE references a file within a folder within the scrapbook that doesn't exist (the folder is there, just not the image file within it). For some reason the actual image file isn't being copied into the relevant folder for use later.
I've not done extensive testing but I'd say this was a bug. If there's a option in Preferences or wherever that fixes this then it isn't anywhere obvious where I can see it. (Or maybe I'm just using it wrong.)
The workaround would be to create the image frames from scratch but, obviously, that's not much help.
Hopefully I'm wrong and someone else can help you better.
P.S. The video you linked to won't play properly for me for some reason so I can't tell if it covers images and I've never tried using images with the scrapbook myself before today so I'm no expert.
Addendum: I've just tried saving the scrapbook under a different name - just to see if the Save function made a difference - but that didn't work either.