Thanks to your alert, I was able to catch the second half of the programme. Excellent footage, eh? Interesting to see the Guaymas Humboldts do to the cinematographer what they did to another photographer, Alex Kerstich, some years ago: charge in from multiple vectors and go for the lights, camera and mask.
The use of red-filtered light at depth (200 ft.) was something I hadn't seen before. Wonder if our friends in NZ are planning to experiment with different filters and wavelengths when attempting to film the really big ones.