Tried to have a look at the 3D-File linked in the Video, but both, the Grip itself and the Inserts just lead to an Error-Page. Also the Link for the Rosette and the Standoff seem to be swapped.
I Personally would want something Protecting that Cable Coming out at the Bottom, so if i set the Camera down or it falls over or something, the Cable wouldnt take all the Stress from that. Extending the 3D-Printed Material Down a bit on the "outside" would do. I would want that material to extend at least 1x or 1,5x the Thickness of the Cable beyond the Point where its Fixed (aka, the Point it would bend from, so the Cable would have at least a bending Radius of something like R=2xD or R=1,5xD, which would be worlds better for that Cable than a Sharp bend at Full Force.
As Far as Mounting goes, i would use this:
https://www.ebay.de/itm/255280846968 (Standard Arri-Rosette with a Slot For Adjustable Mounting on 1/4" Holes)
To mount to the Left Side of My Cage i am Building (see:
https://forum.krontech.ca/index.php?topic=683.0 . Just Posted some Updated Images of the Progress there.). That Plate seems Fine and sure works fine if you dont have a Cage, but as i soon have a Cage, that is just More Streamlined. Still need to Tap these with 1/4" 20TPI, would probably end up using the Lower two of these (see Image).
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Will PM you soon about further Details.