This is actual footage of an unknown species of jellyfish. It was discovered four days into the NOAA ship Okeanos Explorer’s mission to investigate the Marianas (both Islands and Trench). The jellyfish was floating in the waters of the aptly named Enigma Seamount at a depth of about 2.3 miles.
It is most likely a type of hydromedusa, belonging to the genus Crossota. It has two sets of tentacles - one short and one long - and appears to extend the long set in a predatory pose. According to the scientists, “Within the bell, the radial canals in red are connecting points for what looks like the gonads in bright yellow.”
Check out this octopod, found on the last mission of the Okeanos! And follow their remotely controlled submarine dives via this live stream.