There are two versions. The one with the balls is not designed for long arms, heavy lights and strobes, but only for very lightweight rigs (go pros, point and shoots) with correspondingly small lighting.
The big version is for the big rigs, where the lighting is connected to the camera housing in the traditional way and not to the camera mount.
I have the prior version of their pro mount which mounts via a cam band and not the straps, and I actually prefer that overall, although the arca release plate on this new one looks even more robust than mine.
I mount a Nauticam housing for Sony full frame plus a port, and the WWL 1 lens, plus long arms, retra strobes, and a video light, and it is a big and heavy rig (not as bad though as a DSLR with a dome) and even my version of the older pro mount takes it all very well. Scootering with it is a pure joy compared to kicking it around, especially in a current.
The new small one looks phenomenal as a tripod for stationary work. But, I think the allen screws shown on the pro could be removed and a ball mounted there if desired. Would be worth asking Dive-X about that.
OOPS! Just watched the video. Indeed, balls can be added to the pro mount where the allen screw is.