Hi Austin,
yes, thanks, I know that page – I'd wish Ian or Chris would join in here, I think they'd have some answers

I'm sure the guitar in the video (number 5) is a real Ventures II or Mark V with a custom made pickguard and the same tailpiece modification that's been made with all of Johnny's guitars. Nobody would build a German Carve body when the result should look like Johnny's slab

And there have always been enough German Carve Ventures IIs around. I guess John was in need of a new backup guitar after the equipment truck's been stolen again on the first tour with Richie in 1983, so he got that guitar and the red Ventures Mark I, replacing the black slab (and perhaps one the Hamers and the fireglow Rickenbacker?).
The black (custom made?) slab appeared in early 1978 after the equipment's been stolen the first time at Oct. 22, 1977.
Cheers, Max