Enker I got hold of one of these discs to dump, it was Stealth/Wipeout Pure.
So I dumped both isos the way you said.
I looked at the isos in isobuster.
The game iso, had reference to the VIDEO folder but no STREAM folder.
The video iso, had FULL reference to all the game files, but they were zero bytes.
In an ideal world we get a proper dump of one of these discs, I don't think it would work properly ever, or at least not until cfw changes just to support these discs properly.
What I mean is to play the video, you need the iso to be mounted, this then allows you to play the video, but I doubt you could then flick to the game. Anyway.
If you join the game then video, the game works.
If you join the video then game, the video works.
Or you can put one iso (the video iso) in ISO/VIDEO and the game iso in ISO that allows you to watch the video and play the game, the only thing it doesn't allow is mounting the video and then switching to the game, doubt this would ever work even if you injected the game files into the video iso. Which could be done by using Apache, it still would only be to test what happens.
I don't think joining the isos is the way forward they somehow need to be fused into one iso, rather than stuck together.
Years ago when Gran Turismo came out it was Dual Layer on the PS2, and I followed a tutorial that used programs I have long forgotten about, but it involved extracting both layers merging the layers into one then it would work on hdloader, it was long time ago and I have forgotten the ins and outs, it worked anyway, and it was what reminded me about dual layer, layer breaks, which I then spoke about here and IRobot made a tool to find layer breaks.
Anyway I believe these isos need to be merged rather than joined, or used as separate isos.
He who controls the SPICE... controls the UNIVERSE!
The SPICE must flow.