In your reply, you're comparing utterly different shell constructions, not just the volume of glue used. Of course, a ply shell will sound different to a steam bent shell, a ply shell to a stave shell, etc, etc, but it has very little to do with the glue volume, and everything to do with wood structure (or lack of), mass, thickness, and grain orientation - glue volume itself being a minute contributing factor by comparison.
In the video you example, this is displaying the difference between construction thickness, rigidity, mass, and grain orientation - nothing to do with amount of glue, other than it's use to assemble the shell.
In the example on your website, referring to segmented shells, you state "In the end, you have pieces of full wood that can’t vibrate because they are surrounded by glue from at least 3 sides". This is not true on any measurable level of influence. The implication from your statement is that the segments need to vibrate independently of each other to generate an overall construction resonance. This is not the case. A shell resonates as a whole, in fact, the entire instrument resonates as a single entity, including the glue. Nothing resonates in isolation. For sure, segmented will deliver very differently compared to stave, but the amount of glue used, or the number of segment interface bonds, is almost irrelevant in terms of sonic affect outside of resulting diametrical rigidity. All other elements being equal, the biggest difference between delivery of stave and segmented shells is grain orientation resulting in a difference in rigidity, and that lowers pitch + shortens + highlights the fundamental in a stave shell.
We've built, in house, numerous "like for like" shells across two years of R&D, in ply, steam bent, stave, segmented, and hollow log constructions, and carried out extensive testing to isolate the elements that contribute certain characteristics in a finished instrument, so I know, in great detail, exactly what elements equate to both specific and overall affects. Glue volume, in itself, unless using a very heavy resin, has minimal impact.
With the exception of resins - when considering industry standard wood adhesives (i.e. PVA), the vast majority of the applied glue mass evaporates to leave a minute film of no structural consequence in itself. So long as the segments are in intimate contact, there is certainly no "barrier" affect in play. The additional rigidity you find in a ply shell is almost 100% associated with the plies being held in intimate contact with each other / not being able to move (slip) in relation to one another, plus the typical opposing grain orientation. If you move to all vertical grain plies, rigidity is reduced accordingly. If you move to all horizontal plies, diametrical rigidity is increased. The same relationship exists between stave and segmented constructions (assuming segments with horizontal grain orientation), but with overall reduced rigidity compared to ply because of the layup glue bond, but not the residual glue mass itself.
