Hi Babel,
Some of us here at RK remember doing that same clamping off type approach after winding up our lines back in the early days of kite surfing. Though, this may help with reconnecting your lines to the correct corresponding points, it doesn't address the unavoidable twisting of the lines that is occurring when you’re winding up by hand alone.
As a result, we’d end up needing to spin the bar multiple times all while trying to figure out if we’re even spinning the bar in the right direction. Many times even worse than this, you pull tension on those twisted up lines and then they end up knotting up. After a few too many experiences of these types’ of scenarios, we quickly scratch the whole clamping method. You definitely do not have these issues using Quick Connect.
For your question regarding on how to use Quick Connect on a 5th element bar, on the video you’ll note that the Quick Connect is used on the kite lines only. Snap in connection to the kite lines is initiated just beyond the leader lines and center lines. The objective is to maintain lines in order throughout the winding up process and preventing any possible twists. In a 5th line bar or even a 4 line bar, If you there is an attachment point that doesn't fit through the line guide, you unsnap that particular line, by pass that point and snap back in the line continuing with an orderly winding up. Its’ applicable to any bar.
Hope that helps to answer your question