Did those trying it have fully sawn or irregular block or like in the video have the two extruded parallel sides to a decent first grip of the work?
I would have thought that if the block does not have two close to parallel sides to grip initially then you may not get a secure grip without a packer on the moving jaw, with the climb cuts shown a poorly griped workpiece could come loose.
There would also be a limit to size as the longer the cutter needed to reach down the sides the more prone it is to deflection, though if cleaning up all sides completely with the second pass there is no reason to make the initial cuts so deep as you just want enough to rest on a parallel.