Thanks, Marko, that article got me thinking "outside the box". I've got it working now.
Photography
------Camera Raw
------Other
For Camera Raw and Other, I turned off the "Use parent Scheme... " switch.
For Photography, the parent, under "Set rules ...", I put in a rule that selected zero files - in this case: Keyword - is any - (a dummy keyword that isn't used)
I got the camera raw videos under Camera Raw and all the other Photography videos under Other, and none directly under Photography.
That got me exactly what I wanted. Now I can replace the "Other" group with actual categories of Photography videos.
Thanks again,
JW