Been doing some more tests tonight. I'm not convinced that there is any control over ISO or shutter speed at this stage. (using a manual lense, samyang 35mm)
For example if I'm recording at 30fps, I can set it to higher than 1/30th of a second which shouldnt be possible. Setting it any lower appears to make no difference I can discern either.
Also selecting through different ISOs, and the raw histogram stays exactly the same.
When I scroll the camera past a dark scene, to a light scene, and back to a dark scene, the camera is automatically adjusting the exposure to suit.
I havent checked the footage itself yet though... But I would assume it corresponds with the live view image, given that's where the raw file comes from.
As best I can tell there's no way to adjust the "exposure override" settings when it's in movie mode.
EDIT: Here are two frames from a panning shot with no settings adjusted by me:


Another update:
Okay so doing some more checks back home , it looks as though changing exposure works... up to a certain point. I think it just needs a 'lock' at the upper limit relating to FPS.
And it looks like ISO adjustment works now too... super weird. Working in both recording and not.
I definitely had the camera set to 'M' and tried adjusting settings with no luck while out earlier.