Not sure I understand how do you raise the knife to maintain proper angle on the belly and tip?
Don't necessarily have to lift the handle. Doing so would help maintain a consistent
bevel width, which is how most factory edge grinds are done; but ordinarily that would mean the
actual edge angle gets wider (more obtuse) through the belly and tip to keep the bevel's width consistent. Not lifting the handle will keep the
angle consistent throughout, but the bevels will often become wider through the belly and tip, as a result (many of my own knives are sharpened this way, the very first one of which I did with a Lansky guided setup like these). That's usually the trade-off in sharpening a bellied, upsweeping blade; if the consistent-width appearance of the bevels is important to you, you'd want to lift the handle. Otherwise, if a consistent edge angle is more important, not lifting is the way to go. That would also mean it'll usually take more time to grind down the belly and tip to full apex, if it previously was ground for a consistent bevel width, because the edge angle is being much reduced through that portion, and a lot of metal has to come off.
On the topic of the OP, I think one or both of those videos were posted some time back. I seem to recall seeing them. As mentioned, it's basically a much larger 'Aligner' type setup, and looks pretty clever in it's simplicity.
David
