Yep, that's what I said and how I interpreted the intent of the skill as well. There's no reason it couldn't be done neutrally buoyant and in good trim - I know, because that's how I did it (I clearly wasn't in that video
). No mention was made to using it for failed BCDs either, he required a different redundant source of buoyancy that wasn't a DSMB (dual bladder, lift bag, dry suit - though I agree that a drysuit is a horrible idea for redundant buoyancy!). The technique was simply a transfer of some of the buoyancy from the BCD bladder to the DSMB. As you ascend, your bladder goes from negative to neutral and the DSMB goes from neutral to positive. You let go when you're closer to the surface so you're not reeling in 200'+ of line, don't have an absurd amount of rode, and the DSMB location is more representative of your actual location in the water. I would imagine that in an emergency situation (OOG, etc.) your approach would change... but shouldn't that be true of all diving? You make the best decision on course of action based on the circumstances?