OK, thanks for the Transform tab tip, that shows what is happening i.e. when I stretch my head forward, zoom increases by a very small amount.
So I guess I would like to request to be able to set the slider in the 6DOF tab to a much (much) higher value (0.4 is currently the max apparently) so that I can get the non-passthroughed objects in the video to appear to be fixed in reality space. Currently the objects move back when I lean forward, even with the max setting, which ruins the illusion.
Thanks for listening!