I have NO idea what to make of this:
HerrBGone suggested it might be a giant squid of some sort. At first glance the massive squishy surface looked a little like a Colossal Squid, but I can’t see any arms or tentacles, which can be retracted, but the bigger thing is no eyes which on all of these deep sea squid are MASSIVE. Like the size of dinner plates.
Not seeing any major body parts at first I thought maybe its a massive tunicate colony.
Still looking at 4:15 I see what looks like the head and gills of a gastropod.
This page says its a Deepstar Jellyfish.