The video showed he was testing and talking randomly. Airex has the lowest shear strength but the greatest tenacity. Meaning it just stretches and refuses to give up. That is why there is that "rubbery" feel. If you want a flexible boat, use Airex.
A more exhaustive and scientific test on sandwich laminate was made before and was published in PBB a long time ago. Attached is the inset of the article.
A complete study of impact testing on various laminates (includes CF) and cored composites and its effect was in the first edition of Marine Composites by Eric Green and associates. Unfortunately, only the second edition can be downloaded in the net. The impact test and formula was omitted. I have the hard copy of the first edition.