I have had best luck with clamping one panel on edge, then setting the next on top. I look for light gaps, and fine tune the fit with a plane. When the panel on top sits there solidly by itself without light gaps and is in plane with the bottom panel (I check with a straight edge) its pretty much there. Last check is to gently slide the panel a small amount end to end. If it drags slightly (rub joint) then its as good as I can make it. Note: this only works with flat panels, but using the rub joint technique for gluing (panels still on edge) I have successfully glued up as large as a 4 panel layup (one joint at a time) without using clamps. My two panel glue-ups are usually flat on the bench, with minimal if any clamping pressure.
If one of the board is slightly bowed, I do basically the same thing, but clamp the ends to get them in plane and another at the peak of the bow. This requires tapping the top with a mallet to make sure the edges are seated when doing the light gap check. This also requires clamps for gluing.
Beings I usually cut the panel assembly to final length after glue-up, I would be cutting off the compressed ends, negating the advantages of that method.
All of the above is being said without having viewed the videos referenced in the other thread. After seeing them, I may try it again. My previous attempts at spring joints left something to be desired, so maybe I was doing it wrong.