The video is mislabeled. Its title and first few minutes promise an examination of the controversy surrounding the use of dual bladder wings, and I believe that is a very important topic. However, all it did was introduce the issues involved in that controversy without really providing any analysis whatsoever. The rest of the video goes into other forms of redundant buoyancy, none of which have anything whatsoever to do with redundant bladders.
Rename the video "An Introduction to Different Forms of Redundant Buoyancy" and you will have an accurate description of what follows. If it were so labeled, I would not have been so sorely disappointed.